> Take the screws out of the back of the machine, take the cover off, take
> the screw out of the video card, pull it out and look. That'll tell you
> what it is.
> 
> Failing that, booting from a NetBSD generic kernel will probably give
> you some useful information.

XFree86 comes with a utility for probing video cards, I think it is called
superprobe.  That might help.

Ben