955 hands down. ESPECIALLY if you're using the stock cooler. Even if you find the 965 can go slightly higher (which is doubtful when you consider binning and things), you won't have the cooling to aid it. Basically, It's a crap shoot... but the price difference isn't worth it.
EDIT: With the difference, you can buy something like this =] http://www.microcenter.com/single_product_results.phtml?product_id=0315397