Debian sid. I can ping domain names (name resolved quickly). but browser takes ages (about 2 mins) to resolve a url. I adjust the MTU of my NIC to the same value with the one under windows, and disabled ipv6 according to some post on this forum, but still no joy.

(Even, my laptop even timeouts when "telnet www.google.com 80" or "telnet [IP] 80". But this might be another problem.)

'lynx IP' works just fine. 'host domainname' and 'host IP' work just fine. The speed of browsing/downloading is just fine every time after lynx got the IPs, or lftp got the IPs of domain names. The networking under Winxp seems normal.

These are what I got from tcpdump when `lynx www.usc.edu`:
(192.168.0.6 is my NIC, gateway is 192.168.0.1, the ns7 and ns10.attbi.com is the nameserver in /etc/resolv.conf)

09:22:34.459658 IP 192.168.0.6.1043 > ns7.attbi.com.domain: 3747+ AAAA? www.usc.edu. (29)
09:22:39.458444 arp who-has 192.168.0.1 tell 192.168.0.6
09:22:39.459569 IP 192.168.0.6.1044 > ns10.attbi.com.domain: 3747+ AAAA? www.usc.edu. (29)
09:22:39.460586 arp reply 192.168.0.1 is-at 00:09:5b:9f:2a:32
09:22:44.459687 IP 192.168.0.6.1043 > ns7.attbi.com.domain: 3747+ AAAA? www.usc.edu. (29)
09:22:49.459922 IP 192.168.0.6.1044 > ns10.attbi.com.domain: 3747+ AAAA? www.usc.edu. (29)
09:22:54.460287 IP 192.168.0.6.1044 > ns7.attbi.com.domain: 3748+ AAAA? www.usc.edu.we1.client2.attbi.com. (51)
09:22:59.460425 IP 192.168.0.6.1045 > ns10.attbi.com.domain: 3748+ AAAA? www.usc.edu.we1.client2.attbi.com. (51)
09:23:04.460678 IP 192.168.0.6.1044 > ns7.attbi.com.domain: 3748+ AAAA? www.usc.edu.we1.client2.attbi.com. (51)
09:23:09.460924 IP 192.168.0.6.1045 > ns10.attbi.com.domain: 3748+ AAAA? www.usc.edu.we1.client2.attbi.com. (51)
09:23:14.460118 arp who-has 192.168.0.1 tell 192.168.0.6
09:23:14.461248 IP 192.168.0.6.1045 > ns7.attbi.com.domain: 3749+ A? www.usc.edu. (29)
09:23:14.464744 arp reply 192.168.0.1 is-at 00:09:5b:9f:2a:32
09:23:14.520730 IP ns7.attbi.com.domain > 192.168.0.6.1045: 3749 2/2/2 A cwis.usc.edu, (145)
09:23:14.524524 IP 192.168.0.6.1045 > ns7.attbi.com.domain: 3273+ AAAA? www.usc.edu. (29)
09:23:19.524416 IP 192.168.0.6.1046 > ns10.attbi.com.domain: 3273+ AAAA? www.usc.edu. (29)
09:23:24.524592 IP 192.168.0.6.1045 > ns7.attbi.com.domain: 3273+ AAAA? www.usc.edu. (29)
09:23:29.524829 IP 192.168.0.6.1046 > ns10.attbi.com.domain: 3273+ AAAA? www.usc.edu. (29)
09:23:34.525139 IP 192.168.0.6.1046 > ns7.attbi.com.domain: 3274+ AAAA? www.usc.edu.we1.client2.attbi.com. (51)
09:23:39.525346 IP 192.168.0.6.1047 > ns10.attbi.com.domain: 3274+ AAAA? www.usc.edu.we1.client2.attbi.com. (51)
09:23:39.687539 IP ns7.attbi.com.domain > 192.168.0.6.1029: 29 2/6/6[|domain]
09:23:39.687599 IP 192.168.0.6 > ns7.attbi.com: icmp 348: 192.168.0.6 udp port 1029 unreachable
09:23:44.524553 arp who-has 192.168.0.1 tell 192.168.0.6
09:23:44.525556 IP 192.168.0.6.1046 > ns7.attbi.com.domain: 3274+ AAAA? www.usc.edu.we1.client2.attbi.com. (51)
09:23:44.527730 arp reply 192.168.0.1 is-at 00:09:5b:9f:2a:32
09:23:49.525829 IP 192.168.0.6.1047 > ns10.attbi.com.domain: 3274+ AAAA? www.usc.edu.we1.client2.attbi.com. (51)
09:23:54.526163 IP 192.168.0.6.1047 > ns7.attbi.com.domain: 3275+ A? www.usc.edu. (29)
09:23:54.630050 IP ns7.attbi.com.domain > 192.168.0.6.1047: 3275* 2/2/2 A[|domain]
09:23:54.632134 IP 192.168.0.6.1033 > cwis.usc.edu.www: S 1472938783:1472938783(0) win 5808 <mss 1452,sackOK,timestamp 864420 0,nop,wscale 0>
09:23:54.652061 IP cwis.usc.edu.www > 192.168.0.6.1033: S 281057898:281057898(0) ack 1472938784 win 51480 <nop,nop,timestamp 313868834 864420,nop,wscale 2,nop,nop,sackOK,mss 1460>
09:23:54.652118 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 1 win 5808 <nop,nop,timestamp 864440 313868834>
09:23:54.654076 IP 192.168.0.6.1033 > cwis.usc.edu.www: P 1:217(216) ack 1 win 5808 <nop,nop,timestamp 864442 313868834>
09:23:54.689054 IP cwis.usc.edu.www > 192.168.0.6.1033: . ack 217 win 51480 <nop,nop,timestamp 313868837 864442>
09:23:54.718038 IP cwis.usc.edu.www > 192.168.0.6.1033: . 1:1441(1440) ack 217 win 51480 <nop,nop,timestamp 313868840 864442>
09:23:54.718078 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 1441 win 8640 <nop,nop,timestamp 864506 313868840>
09:23:54.726043 IP cwis.usc.edu.www > 192.168.0.6.1033: P 2881:4321(1440) ack 217 win 51480 <nop,nop,timestamp 313868840 864442>
09:23:54.726128 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 1441 win 8640 <nop,nop,timestamp 864514 313868840,nop,nop,sack sack 1 {2881:4321} >
09:23:54.728034 IP cwis.usc.edu.www > 192.168.0.6.1033: P 1441:2881(1440) ack 217 win 51480 <nop,nop,timestamp 313868840 864442>
09:23:54.728074 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 4321 win 11520 <nop,nop,timestamp 864516 313868840>
09:23:54.750036 IP cwis.usc.edu.www > 192.168.0.6.1033: . 4321:5761(1440) ack 217 win 51480 <nop,nop,timestamp 313868843 864506>
09:23:54.750087 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 5761 win 14400 <nop,nop,timestamp 864538 313868843>
09:23:54.755032 IP cwis.usc.edu.www > 192.168.0.6.1033: . 5761:7201(1440) ack 217 win 51480 <nop,nop,timestamp 313868843 864506>
09:23:54.755069 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 7201 win 17280 <nop,nop,timestamp 864543 313868843>
09:23:54.757031 IP cwis.usc.edu.www > 192.168.0.6.1033: . 7201:8641(1440) ack 217 win 51480 <nop,nop,timestamp 313868844 864516>
09:23:54.757056 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 8641 win 20160 <nop,nop,timestamp 864545 313868844>
09:23:54.774075 IP cwis.usc.edu.www > 192.168.0.6.1033: . 10081:11521(1440) ack 217 win 51480 <nop,nop,timestamp 313868844 864516>
09:23:54.774209 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 8641 win 20160 <nop,nop,timestamp 864562 313868844,nop,nop,sack sack 1 {10081:11521} >
09:23:54.800025 IP cwis.usc.edu.www > 192.168.0.6.1033: . 11521:12961(1440) ack 217 win 51480 <nop,nop,timestamp 313868848 864538>
09:23:54.800055 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 8641 win 20160 <nop,nop,timestamp 864588 313868844,nop,nop,sack sack 1 {10081:12961} >
09:23:54.812023 IP cwis.usc.edu.www > 192.168.0.6.1033: . 12961:14401(1440) ack 217 win 51480 <nop,nop,timestamp 313868848 864538>
09:23:54.812057 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 8641 win 20160 <nop,nop,timestamp 864600 313868844,nop,nop,sack sack 1 {10081:14401} >
09:23:54.816017 IP cwis.usc.edu.www > 192.168.0.6.1033: . 14401:15841(1440) ack 217 win 51480 <nop,nop,timestamp 313868848 864543>
09:23:54.816045 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 8641 win 20160 <nop,nop,timestamp 864604 313868844,nop,nop,sack sack 1 {10081:15841} >
09:23:54.818022 IP cwis.usc.edu.www > 192.168.0.6.1033: . 15841:17281(1440) ack 217 win 51480 <nop,nop,timestamp 313868848 864543>
09:23:54.818053 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 8641 win 20160 <nop,nop,timestamp 864606 313868844,nop,nop,sack sack 1 {10081:17281} >
09:23:54.820020 IP cwis.usc.edu.www > 192.168.0.6.1033: . 17281:18721(1440) ack 217 win 51480 <nop,nop,timestamp 313868849 864545>
09:23:54.820046 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 8641 win 20160 <nop,nop,timestamp 864608 313868844,nop,nop,sack sack 1 {10081:18721} >
09:23:54.822020 IP cwis.usc.edu.www > 192.168.0.6.1033: . 18721:20161(1440) ack 217 win 51480 <nop,nop,timestamp 313868849 864545>
09:23:54.822047 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 8641 win 20160 <nop,nop,timestamp 864610 313868844,nop,nop,sack sack 1 {10081:20161} >
09:23:54.852015 IP cwis.usc.edu.www > 192.168.0.6.1033: . 8641:10081(1440) ack 217 win 51480 <nop,nop,timestamp 313868853 864600>
09:23:54.852051 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 20161 win 23040 <nop,nop,timestamp 864640 313868853>
09:23:54.869054 IP cwis.usc.edu.www > 192.168.0.6.1033: . 20161:21601(1440) ack 217 win 51480 <nop,nop,timestamp 313868855 864606>
09:23:54.869175 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 21601 win 25920 <nop,nop,timestamp 864657 313868855>
09:23:54.874015 IP cwis.usc.edu.www > 192.168.0.6.1033: . 21601:23041(1440) ack 217 win 51480 <nop,nop,timestamp 313868856 864608>
09:23:54.874065 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 23041 win 28800 <nop,nop,timestamp 864662 313868856>
09:23:54.887010 IP cwis.usc.edu.www > 192.168.0.6.1033: . 23041:24481(1440) ack 217 win 51480 <nop,nop,timestamp 313868857 864610>
09:23:54.887056 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 24481 win 31680 <nop,nop,timestamp 864675 313868857>
09:23:54.891007 IP cwis.usc.edu.www > 192.168.0.6.1033: . 24481:25921(1440) ack 217 win 51480 <nop,nop,timestamp 313868857 864640>
09:23:54.891038 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 25921 win 34560 <nop,nop,timestamp 864679 313868857>
09:23:54.893008 IP cwis.usc.edu.www > 192.168.0.6.1033: . 25921:27361(1440) ack 217 win 51480 <nop,nop,timestamp 313868857 864640>
09:23:54.893042 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 27361 win 34560 <nop,nop,timestamp 864681 313868857>
09:23:54.911006 IP cwis.usc.edu.www > 192.168.0.6.1033: . 27361:28801(1440) ack 217 win 51480 <nop,nop,timestamp 313868857 864657>
09:23:54.911036 IP 192.168.0.6.1033 > cwis.usc.edu.www: . ack 28801 win 34560 <nop,nop,timestamp 864699 313868857>
09:23:54.913002 IP cwis.usc.edu.www > 192.168.0.6.1033: FP 28801:29873(1072) ack 217 win 51480 <nop,nop,timestamp 313868858 864662>
09:23:54.915056 IP 192.168.0.6.1033 > cwis.usc.edu.www: F 217:217(0) ack 29874 win 34560 <nop,nop,timestamp 864703 313868858>
09:23:54.941002 IP cwis.usc.edu.www > 192.168.0.6.1033: . ack 218 win 51480 <nop,nop,timestamp 313868863 864703>

Any suggestion appreciated!

In /etc/resolv.conf do you have the IP's of your providers primary and secondary nameservers?

Yes, they are in IP forms.