Im buying a new graphic card and I need your help to chose

Depending what your using it for and what games you play... I'd say GT630 for the 1gb but I don't know what prices your looking at. Obviously 1GB will run higher resolutions in games and desktop and more texture.

I agree..Sitting on 512MB of memory on a video card isnt healty at all and the 1GB will help with textures and resolutions and such.

Whats your budget? I'm guessing if you are looking at these cards its fairly low, around $75 if Newegg prices are right.

I suggest scrounging up another $20 and getting a HD7750.
Sapphire HD7750. $95 ($10 rebate)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I'm going with the 6670. I can't find a review of the GT630, but from what I can tell of the specs its really a low end card. Probably not much faster then then a GT430, which was a horrible gaming card. Who cares if you have a gig of ram for textures and details if the chip itself isn't powerful enough for it?

6850 as a minimum!! 7850 would serve you even better.

hold out a bit for the 7750 it dominates the 6670. It is nearly 2x faster...

GT 630 is a rebadged GT 440  

I'd get 6670 over GT 630.

But for a few bucks more you could get a 7750 which is 50% faster.