Thermalright SI 120 has gotten some really good reviews. I'm getting ready to install a Thermaltake Tower112 today, and although it looks like it'll do the job, it is really heavy. The SI 120 looks to be pretty light in comparison, and used along with a good fan, should work really well....from what I've read about it anyway.
i OC'd my bro's 3000+ venice to 2.7GHz on air cooling.
wich is now under full load at 63*C ( and that with a 50% speed increase)
so, i cn only reccoment this one.
its very light , about 500g. its really easy to fit, it has 5 years of warranty ( keramic bearings) and it comew with good thermal paste
and it is super silent