You will need to get a new CPU heatsink for sure if you are planning on doing any OCing.
The i7 runs ridiculously hot (run coretemp, and you will know what I mean).
Anything below 3.6 should be doable with air. Anything >3.6 you will need water-cooling IMO.
As for OCing guide for the i7:
http://www.tomshardware.com/forum/25...clocking-guide
What I did:
got a new CPU heatsink, OC it to 3.2 (very mild OC).
Temperature remains the same as when it was at 2.66 w/stock heatsink.
-KC