Help, weirdest XP Pro Networking problem ever.

So I've been running Windows Vista Ultimate x-64 without a hitch for the last 4-5 months (minus the Nvidia display driver randomly crashing all the time) and am trying to switch back to Windows XP Pro.

Once I install XP Pro and update all my drivers from the Nvidia/Asus sites I cannot connect to my network or the internet. The strange part about this is that my computer gets a valid IP address, lease time DNS servers etc and lists them all under the support tab for the network controller yet I can't log onto my router, ping my router, or any other website. Also I can log onto my router from my other computer and it shows it listed under the DHCP list.

Oh 1 other thing as well, I reset this router incase some how some mac filtering or some such got on there, no go; I also bought a new router to test it out and it had the exact same problem. This is all leading me to believe the problem lies somewhere in XP Pro.

As for the system

BFG Gforce 8800 GTX
AMD Fx-70 (yes, I know, I got a really good deal on it though, like.. really cheap)
4x1gb Corsair Dominator
(Both lan connections on this board do the same things.)