Glad you got it working Lemur but it seems your Pc set a bad precedent...

Started my PC today, everything was normal, and right in the process of doubleclicking the COH:OP shortcut in SteamI got a blue screen, first one in Vista I think. IIRC it said IRQ_NOT_LESS_OR_EQUAL and at the bottom mentioned an usbsomething.sys.
Restarted and there was nothing
Fans fired up, HDD seems to work as well, no beeps but a blank screen, turned it of, tried again, same thing but now the graphics card fan always goes to full power and stays there. Thought the GPU might be fried.
Then I had an idea, why not try the integrated graphics, took the GPU out and connected the monitor to the mainboard DVI, but same thing, blank screen, thought okay, they're disabled in the BIOS so I tried resetting CMOS, no go, put the GPU back in, still nothing but the fan now goes to full speed, slower again, back to full speed etc.

So I fear it might also be the mainboard, if anyone has some advice I'd appreciate it because taking the whole PC to the shop requires me to call, and pay for, a taxi so if a component could be isolated and exchanged that might be a big help.