It wasn’t so very long ago that the 4870 was the king of the hill. They offer it all the way up to 2GB right now, but 512MB should suit anybody shopping in the mid range. And $150 (with the $15 mail-in rebate) is an absolutely excellent price for this card. If I weren’t completely broke right now, I’d buy one myself. Maybe one of you guys could buy two and I’ll pay you back when I’ve got more GP?
Don’t forget that it’s a “double-wide.” Make sure you’ve got space in your case.