It is not clear-cut
gt630 is re-badged gt440. not a great card.
The 9600gt is quite old now, but will outperform the gt440/630 in a number of areas due to a better memory bus (256bit vs 192bit for the gt440/630).
On the other hand the 630 has a newer architecture, lower power requirements, supports dx11 and will do AA faster. Though to get good framerates you will prbably need to turn off AA/DX11.
the Radeon 4850 is around the same price and will be better than either of these cards.