I've intel P4 915 Express chipset motherboard, i 've recently i've dual booted fedora core 6 (GUI installation) along with WinXP(previously installed) on the system, it does work for couple of days, 3D acceleration works best,it was much powerful and attractive .
But after few days fedora shows problem during P.O.S.T while detecting Network card and unable to proceed further
i've reinstalled it again but same problem occurs , so i've to replace fedora with Suse 10.2(which is fine ,working since a month but not like fedora) to save the MBR and windows.Can any plz sujjest me what could be the cause problem and what kind of precautions to take while installing new Fedora core again.

There are different possibilities. You may check the output of lspci,dmesg and lsmod.

lspci - Shows you your available devices in your computer. Mine shows:
[root@speedy ~]# lspci|grep net
00:12.0 Ethernet controller: VIA Technologies, Inc. VT6102 [Rhine-II] (rev 7c)

dmesg shows you kernel boot messages. If your network hardware is successfully detected there should be something like:
[root@speedy ~]# dmesg|grep -i eth0
eth0: VIA Rhine II at 0x1e800, 00:19:66:01:a0:06, IRQ 23.
eth0: MII PHY found at address 1, status 0x786d advertising 01e1 Link 45e1.
eth0: link up, 100Mbps, full-duplex, lpa 0x45E1
eth0: no IPv6 routers present

lsmod shows you loaded kernel modules:
[root@speedy ~]# lsmod| grep -e mii -e rhine
via_rhine 23432 0
mii 5632 1 via_rhine


You probably need other kernel modules for your hardware. However, every recent distro compiles every
available module, and makes it available for you.

You may consider to compile a kernel.