I just felt old and out of the loop. AMD has announced that they think 4 GB RAM on a video card is too little for current gaming, and think the lower end should be raised to 6-8 GB. On the video card, not on the computer itself.
Haha! I love it! With this much RAM, I don't have to optimize anything! I don't even have to maintain a physically solid form! *melts into a gelatinous blob, laughing maniacally*
It unfortunately is too little if you plan on playing the cream of the crop at the highest settings. Even 8GB is quickly becoming an ideal bare minimum.
If you're not playing the latest system pushers, 4GB is fine.