speaking of least expensive then get the HD 6450 with DX 11 and Shader Version 5.0
But dont expect to game modern games but u will play games released before 2010 with good FPS.
Further Telling us ur CPU speed and ram and anything else and what u wanna do with the card will let us help u.
Thanks for the suggestion, we're not looking to spend more than we have to. This PC is not for any games or movies, just browsing Facebook, checking e-mail, and reading News sites. Here's the specs
Pentium E5800 3.2 GHz Dual Core
3GB DDR3 Ram
PUS is only 220W
Any other thoughts would be great, thanks