You could get by with just the i7 920 if you OC it properly, but definitely get an aftermarket cooler, as those CPUs run hot. I would recommend something like the Titan Fenrir TTC-NK85TZ. You could easily OC to 3 to 3.4 Ghz with that cooler.
Many coolers including this one are based on the exposed heatpipe design Xigmatek made famous, but none do it as well as Titan. This unit is not only beautiful, it has whopping 8mm heatpipes and a very quiet low profile fan that auto adjusts it's speed.
It's very reasonably priced too.
http://www.frostytech.com/articleview.cfm?articleID=2383
I would lean toward the ASUS MB and just out of curiosity, what case are you throwing all this into?
Oh man, that Titan cooler looks awesome, it's a pity that I can't find it on local hardware websites. Actually Taitan is not even within the brand list. What I have here is actto, ANTEC, Arctic-Cooling, AVC, Calibre, CHOIIX, Coolink, CoolJag, ENERMAX, idock, Thermalright, Tt, ZEROtherm, Corsair, Cooler Master, etc.
Anyway I've managed to spot some discussions in a few local forums, confirming that the price is indeed quite reasonable. I will consult local dealers to find out if it's gonna be available.
My current case is of a local brand. It came in good quality, and I bought it for 70 bucks.
I just realized that this forum might not allow attachments. So I have to put it up elsewhere:
I've built a digital thermometer and fit it into one of the CD bays. Right now, with room temperature at 23C(73F), I'm getting 27.8C(82F).