
Yeah if you're in the market for a card in that price segment Rad9000 is by far the best bet. Rad9000 should be about 20% slower than Rad9000PRO but it should o/c very well. Rad9000PRO is nearly always slower than Rad8500LE which in turn is 10% slower than Rad8500. All Rad8500/9000 cards offer full DX8 hw which is well worth having as well as much better perf than GF2 or GF4MX cards.

In terms of where the GF3 cards slot in, GF3TI200 is way down at defaults but o/c's to about GF3TI500 speeds and that's why they're so popular. GF3TI200 at deafult tends to be a tad slower than Rad8500LE while Rad8500 usually falls just behind GF3TI500, the perf of all these cards are very close and ALL support full DX8 hw unlike the GF2, GF4MX and Rad7500 which are all DX7 card technology from a few years ago.

Regarding things other than raw perf, GF3 cards only advantage is possessing good AA, Rad8500/9000 cards are hugely better with image quality, TVout, dual display (depending upon manu) and DVD playback. This is why nVidia revised GF3 technology with the GF4TI cards which enhanced 3D perf, AA, image quality, dual display and ability to really take advantage of the fastest CPUs. In terms of o/c'ing each model GF4TI tend to o/c to the level of the one above it, 4200=4400, 4400=4600 but 4600 being the top tends just gets +5%.

nVidia brought in the GF4MX cards for much the same reasons as the GF4TI cards, to fill in the gaps where Radeons hurt them the most. GF4MX cards are all essentially enhanced but largely unchanged technology (ie DX7). The enhancements are significant as they really improve 3D perf, image quality, TVout, dual display and DVD playback but you're still getting technology from a couple of years ago. 3D perf is still way slower than GF3TI200,
Rand covered the GF2 and GF4MX cards' perf so check out that ... but really the Rad9000 is the lowest card you should consider with the Rad8500, 8500LE, 9000PRO all costing little more and really being where you should aim. GF3 cards are fine alternatives esp if priced lower and you do gain AA but at the expense of the things outlined above.
EDIT:
Toms VGA Charts
Tech-Report Rad9000PRO
AnAndTech Rad9000PRO
X-Bit Labs GF4MX cards (Note: Rad7500 is SDR rather than the usual DDR)