Isolated a problem with a new build, not sure how to fix! Help!

I recently built a new system - Core i7 860 on a P7P55D PRO, Radeon HD5850.

Just about everything seems to be working fine, except for my wireless adapter. I went and got a USB 802.11n adapter after the PCI card I had originally bought would completely freeze windows before it would even load Windows 7 x64 (tried safe mode to install latests drivers, wouldnt work, and other cards do work in PCI slots).

Under many conditions, my WiFi works relatively well. The real problem arises when my CPU is under "heavy" load. Now, I don't just mean 8 threads of Prime or ITB. Simply installing Steam backups (which uses 1 core while the other 3 sleep) completely wipes out my wireless.

I'm assuming it has to do with priorities being given to programs before the USB adapters, but even lowering Steam to lowest priority still wouldn't give me WiFi - it would keep on going and using my whole core.

Is there any way to increase the priority of the USB controller? Is this OS or MoBo related?

Thank you very much for any input.

ps: I know this isn't the WiFi forum, but they're a lot less active, and you guys tend to know a lot more about the different settings of a system...

Yea, I already disabled that AND in power options removed selective USB power management.