Wireless internet slowdown

When I OC an C2D E6750 on Gigabyte mobo using Easy tune5 to OC my wireless internet slows down to 10% or so. Wired connection is fine.
Wireless card is Linksys PCI Card WMP54G.
Any ideas?

OS is XP PRO SP3.
 
Tried, but I must do something wrong. It restarts every time BIOS post.


Gigabyte Model 965P-DS3 rev.3.3

Processor Intel(R) Core(TM)2 Duo CPU E6750 @ 2.66GHz, 2667 Mhz, 2 Core(s)

Was working on XP for some time (about 2 years, than it stopped working for about a year), but Win7 never worked. I OC up to 3.1Mhz, even @ 2.7 it restarts @ posting.