Question : How to fix TCP/IP stack

I have windows XP Professional on my laptop which has a NIC and a wireless cardbus.
Both can get IPs from the router (DHCP).  I can ping the gateway (router) or ping outside world
by names (i.e. yahoo.com, google.com..etc).  I can see and map other computers on my LAN..
But by some reason I can not browse the Internet, even I use both MS Internet Explorer or Firefox.  I'm not sure but I think something wrong with the TCP/IP stack.  I downloaded and ran WinsockxpFix, but still no luck.
Please help

Thank you very much.

Answer : How to fix TCP/IP stack

Olddalat--You can consider doing a Repair Install which should not affect your personal data.
However that also requires a WinXP CD of the same SP that you now have on the PC.  Use the Product Key that came with the PC.
http://www.dougknox.com/xp/tips/xp_repair_install.htm
http://www.michaelstevenstech.com/XPrepairinstall.htm