AMD's Sempron 140 is here to seal the deal in the entry level market for $39. It offers all the features of the K10.5 architecture, but comes with only a single core at 2.70 GHz. Despite its single core it offers decent performance for every day office use, media PCs and casual gaming. If you get lucky you might even be able to unlock a second core.

http://www.techpowerup.com/reviews/AMD/Sempron_140