
Yeah I'm guessing your limited to PCI hence the choices in cards. It is worth rem'ing that an AthlonXP and SktA mobo may be all you need and cost XP1600+ $53, XP2000+ $90 with SktA mobos around $50. If you absolutely need to choose between these low end gfx cards then it really does depend upon what Radeon you mean (is it SDR, DDR etc), your reqs and also what CPU you're using.

GF4MX420 is under-rated and gives near GF2GTS perf but with the GF4 enhancements such as image quality, dual display, slightly enhanced TVout/VIVO and hw DVD playback. GF4MX440 tends to be faster than any GF2 card inc TI and Ultra and obviously sports the GF4 enhancements. The Radeon cards do tend to still be better in terms of image quality, TVout and hw DVD playback although it is pretty close. So I'd dismiss GF2MX cards and choose between GF4MX or Rad7500/9000 cards presuming you're stuck in PCI.

As for Radeon perf, Radeon7000/VE gives roughly GF2MX perf, Rad7500 gives GF2GTS-TI perf, Rad9000 only has Rad7500 perf but is the only one of these cards to support DX8 hw just like the GF3 and Rad8500 cards, plus it should o/c well too. Here's some reviews, note they use AGP and you'll lose about 20% perf going to PCI:
TomsHW Rad7000/VE
AnAndTech Rad7500, GF2MX400 etc review inc some CPU scaling
Guru3D GF4MX420 review
Tech Report Rad9000PRO review (20% faster than Rad9000)
EDIT: As for TV abilities the AIW are tops, nVidia Pers Cinema are still decent while most GF4 come with VIVO ability which comes on very cheap. You may want to consider a seperate PCI TVcard, esp with the speed at which the gfx market is moving, plus you can take it over to your new PC when you do upgrade.