from an unbiased point...
r300 aka radeon 9700 is the fastest and also the driver team that is working on it happens to be same guys who used to work on the driver team for detonators... therefore catalyst is gaining some recognition as being a good set of drivers... unfortunately those who do not use ati cards will not know this...
nvidia has a very good set of cards in the g4 series and I am definitely a fan...
www.tcwo.com call them up and ask for their MSI g4 ti4600 I saw it today at their store for around 269 USD... which is a very good price since the MSI version of the ti 4600 is consitently one of the best solutions in its class...
now for the 9700... why NOT buy it? it is only a little more expensive than the 4600, has support for dx9 and has agp 8x support... you are getting a nextgen for the price of something that was designed for FULL dx 8.0a support... not 8.1 (read product specs)
also the speeds matter... g4 does not come close to speeds of the 9700 if you compare test to test... if AA is turned on for the 9700 then yes they are close... but AA gives a massive hit.. if AA is turned on both cards you are easily going to see the 9700 win...
the new dets... the 40.x series give the 4600 a MASSIVE boost in the nature test for the 3dmark2001 SE test otherwise there is no other real improvement... a few fps tops... worthy yes... but it is not as massive a performance boost as everyone claims... remove the nature scores and the det 40.x series is a good driver release, but not as spectacular as the 1000 point increases you will see in 3dmark...
if you WANT to buy a card now and have the money... get the 9700... if you want to wait for a nexgen card wait for the r350 0.15 micron process card from ATI... the 0.13 micron process nv30 from Nvidia or the R350/R400 0.13 process solution from ATI that comes out end of this year/early next year...
also please do understand that ATi had a supposedly bad driver support compared to nvidia... fact is they just don't release drivers as often as nvidia... you can take that many ways... either nvidia has a problem therefore need the releases, ati does not need the releases due to their drivers having good enoughstability/performance already, nividia has better care for its customers therefore releases on a regular basis... am sure there are other reasons too that I could include but I don't want to start a flame war
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also catalyst drivers are being released officially on a regular basis and there are many beta releases of catalysts too..
if money is no issue get a 9700... or a 4600 which is NOT nexgen... or wait for r350 or nv30...
do not get lower than a 4600 if price is not a factor... 4200 is MUCH slower than a 4600 @ default clocks...
my 2cents.... and more