I always go for an aftermarket heatsink/fan.
Here is a good one for less than$20.
http://www.newegg.com/Product/Product.aspx?Item=N82E16835119091
I think the Phenom II 965 is kinda priced too high although the price recently dropped substantially by $30 in the last few days from $245 U.S. to $215 U.S. over at newegg.I prefer the Phenom II 955 myself because the price is much lower $180 U.S. or $35 less than the Phenom II 965.
The i5 would be better (the CPU easily outperforms the Phenom II's especially when over clocked) unfortunately there have been reports about defective sockets on that platforms motherboards.Also some other problems with some motherboards.Until it's worked out I would avoid it for a few months.
The i7 920 on the X58 Platform is incredible and no problems with it.
Well worth it's price although it's more expensive.
See the CPU recommendations here or at the top of the forum.
http://www.tomshardware.com/forum/267801-28-buyer-guide