Have you re-started your computer since setting up the wireless connection? I've sometimes found that when I've switched connections, it hasn't worked properly until I've restarted.
If yes, I'd suggest trying the following in a terminal window while connected to wireless, to see if it gives any clues:
$ /sbin/ifconfig # Does this show a configured interface named something like "wlanX"?
wlan0 Link encap:Ethernet HWaddr 00:19:d2:ab:cd:ef
inet addr:192.168.1.85 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::219:d2ff:feab:cdef/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:162887 errors:0 dropped:0 overruns:0 frame:0
TX packets:108354 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:195527132 (186.4 MiB) TX bytes:14756548 (14.0 MiB)
$ netstat -rn # Do you have a route defined to "0.0.0.0" for this interface?
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0 wlan0
$ nslookup www.linuxquestions.org # Can you resolve a domain name?
$ nslookup www.linuxquestions.org 184.108.40.206 # If not, does it work using Google DNS server?
$ ping www.linuxquestions.org # Can you ping by domain name?
PING www.linuxquestions.org (220.127.116.11) 56(84) bytes of data.
64 bytes from www.linuxquestions.org (18.104.22.168): icmp_req=1 ttl=47 time=136 ms
64 bytes from www.linuxquestions.org (22.214.171.124): icmp_req=2 ttl=47 time=135 ms
$ ping 126.96.36.199 # Or by IP address?
PING 188.8.131.52 (184.108.40.206) 56(84) bytes of data.
64 bytes from 220.127.116.11: icmp_req=1 ttl=48 time=40.1 ms
64 bytes from 18.104.22.168: icmp_req=2 ttl=48 time=35.3 ms