new build..HELP

[DarkSide50420]

so yea i sold my 3700+ sandy last night and now im going to need a new cpu.. im on quite a tight budget.. s939 is what im looking at so i wont have to upgrade ram..

will also need a good sli mobo which im thinking of that matx sli evga mobo for $53.xx at the egg..

what cpu should i go with?