I had already gone here and downloaded and installed this driver (http://www.nvidia.com/object/winxp_190.62_whql.html
), so I think I got the right one. But, if anything, it made the problem worse.
One thing of interest - I had an old XP disk, so it re-installed up through SP1. I also didn't have the right driver at that time, so Device Manager had a question mark for the video card, but it worked (same problem with slowness). But I never got the flashing and freezing until after I installed SP3 and the Auto Updates.
I'll probably restore back to the post SP3, pre Auto updates and see if it seems to work OK. That would most likely tell me it's a function of the Auto Updates.