ForceWare 30.82 and 45.23 have been super solid for me. Used the former with a TNT2 and the latter with tons of Nvidia cards, including a GeForce 256 DDR. No idea if either of those is the best performance-wise but they both rock from a stability and compatibility standpoint. I think those were crowd favorites, judging from old forum posts.

Sorry it's taken two months to reply, busy times 😀

I gave 28.32 WinXP drivers a go and they do seem quicker than the 61.77 I was using previously. 3DMark2000 has jumped from 4800 up to 5200 which is more like what I expected to see (using Phil's GeforceDDR video as a reference - he's getting 5400 but with a P4 2.something Ghz, whereas I'm on a PIII 933).