Just replaced the stock fan with a HR-03. As you can see, there are two mounting options. One is the size of the 6-hole bracket, the other one (bigger) is the standard 4-hole mount. I used the smaller one. 8800GTS/GTX coolers will not work though, too big.
Temps:
37C Idle / 47C Load
(I think I put a little too much paste though...)
And now with the overclocking