The GeForce 4 MX440 (stay away from SE - 64 bit memory bus) is a great choice for DX7 games and earlier (excluding glide). It can often be found for very cheap. At the time it provided better than GeForce 2 Ultra performance (in most titles, noting the GF2 Ultra had 2x the amount of TMUs so would win some benchmarks). I would get this over a GF1 or GF2 of any variant if your on a budget and don't care for collecting high end period correct cards.
If you're looking fora DX8 card, the Ti4200 is probably the best and cheapest option. It outperforms a Ti500 and you can pick them up for a reasonable price if you're patient.
As someone has already said, PixelPipes review of the FX5200 Ultra showed it was slower than a Ti4200 in most tests. Other models of the FX series, such as a FX5600 (stay away from the XT most have a 64 bit memory bus), FX5600 Ultra or FX5700 (again avoid the VE and LE models - 64bit memory bust) can be found for cheap too - hopefully other people can comment on their performance as I dont have much experience with the FX series.