Cheers for the replies! Here are some answers of the top off my head;
No, there isn't a BIOS setting to disable on board video.
No, there isn't a jumper on the board or mentioned in manual.
No, onboard performance isn't acceptable. I mean I'm noticing a fair few games dipping bleow or running at half frame rates which I'm sure I've seen running okay on slower PC's.
Yes, I can update BIOS but it's hardly old as it is! Certainly much newer than my Geforce card, plus this PC is bare bones - no modem etc.
Yes, there is another PCI slot to try but slot 1 which I'm using is what the BIOS says to use for video. Plus I gotta break another metal tab off my case just to try it

Yes, I've tried the latest Nvidia drivers which install fine but make no difference. Anyhow, shouldn't it start in safe mode at least without drivers?
Yes, I can try the card in another PC. But I'm 99% sure it will work fine as it always has.
The model number of my board is: GA-7VM400AM(F) VIA KM400A Chipset. Tiger Heli I hope this tells you something that might help.
I just wanna play NBA jam, puzzle bobble 2, mk etc at 60fps.