*Edit* I think you want the 2000/xp/2003 nForce500 Series Chipset Drivers.
I would give it a shot. If all else fails, you can contact their tech support. They are pretty good at getting back to your questions within a few hours of submitting them (I'm sure this is one of the first questions they will ask you as well).
Er, just thought of something also - are you using a drive emulation software? Daemons Tools, Alcohol 120%, etc.?