The RIVA TNT is out for several months now and most people agree that it is currently the best 2D/3D solution available. Its only real competitor is the cheaper Voodoo Banshee, a 2D/3D chip that is performing worse than TNT, but which is taking advantage of the powerful brand name 3Dfx. The performance of TNT is only surpassed by 3Dfx's Voodoo2 chip, but you need two add-on 3D-only accelerator cards with this chip to really achieve better performance than TNT. Two Voodoo2 cards are considerably more expensive though and you won't necessarily experience a major difference in 3D gaming. The 3D image quality of TNT is definitely way ahead of products with 3Dfx chips and only the upcoming Rage 128 chip from ATI could give NVIDIA's RIVA TNT a real run for its money.
TNT cards are usually running at 90 MHz chip clock and 110 MHz memory clock by default, but in many cases it's possible to successfully overclock the TNT. The chart above shows that a RIVA TNT overclocked to 120/125 MHz can easily surpass ATI's upcoming Rage 128 and it is getting pretty close to the 3D performance of two Voodoo2 cards in SLI mode. All in all the TNT is certainly the most attractive 2D/3D solution available today, so that you only need to know which particular TNT card to get.
There are currently seven card makers who supply a 2D/3D card with the RIVA TNT, six of them are represented in this test. The only missing card is from Canopus, it was unfortunately not available to me for this test.