The GTX260 is about the same as an HD6850. The 5770 is old school just like the GTX260.
The newer GTX460's do DX11 and also do Physx that a lot of the newer games have, ATI doesn't do Physx.
The i5 2500 is the new Sandy Bridge CPU that Intel just came out with.
Think i5 2500 and GTX460!
The above parts would future proof you for quite a while.