Definitely ati readeon hd 5470 is much better than the gt310 ....well both of them are for light gaming only.....but hd5470 has an upper hand with the support of dx 11...while gt310 has dx 10.1 only...so go for the ati readeon hd 5470
Yes, HD5470 is better, but it's still a low end card (weak) for gaming purpose, but if you only doing some office work like docs or watching videos then both of cards are okay...