shweet, +1's for me. no but seriously, the HD4670 has a lot more features then the HD3800 series, it consumes the same amount of power as the Nvidia 8500gt(and the 8500gt is nothing compared to the hd4760).
it's also a nice cool card and plays all the new games which some eye candy
HIS 4670, that extra RAM will only help you on very high resolutions, as SharkBait said. It's overclocked, has a better and quieter cooler, so I'd say it's worth the extra cash.