Best Video Card for an HP 700-149

Hello,

I bought an HP 700-149 because it was a decent price, I know HP, specs were good.  Except for the video card.  For a high end machine, the video card is pretty basic.  It is an NVIDIA GeForce GT 635 (2 GB DDR3 dedicated) which is pretty poor - for gaming.  For Office - it works just fine.  But I like me games.

I would like to get a better video card - and stick with Nvidia.  The power supply on this machine is 460W.  Any suggestions on what to put in it?

Thanks,

VP