The 5770 is more money than a 460 or almost. I'd rather suggest the 460 since you only have 1 16x slot anyway so go with the 460 if you do want to get a new card. But even if you do get one, your CPU will bottleneck it, that's assured. Be sure to check your PSU as well if you upgrade your GPU.
But... I highly suggest you build an entire pc entirely. Your CPU and PCI slot (it's not 16x 2.0, but still a 16x 2.0 card will work on it) will bottleneck the performance alot.
Currently i dont have enough money for anything else and i was thinking maybe i should get a new gfx, it will atleast improve my performance, and then when i have more money ill get a new mobo,cpu, and what not. maybe even ddr
The less money i spend the better, however i do want have a decent performance on average res, 1280 x 1024, and i dont want to play them on the highest possible graphicx just on a playable level and decent framerate.
im not picky seeing as my current gpu isnt the most powerful thing in the world
I wont be upgrading the whole thing until few years and graphic card i need is only for a years or so just so i can play some games, other wise ill have to buy an Xbox and as a very big fan of PC i feel that that would be a betrayal.