I've got a watercooling system for my CPU; I got the parts from
Pc Case Gear, and
Gam Mods
but since you're on a budget, you'd be looking at air cooling.
I have used a Thermaltake Sonic Tower pretty successfully on a Sempron 2800+, X2 4600+ and X2 6000+
staticICE :: sonic tower : Australia's comprehensive computer hardware and gadget price comparison search engine
the 6000+ I have is a 120W model, and I did overclock it, so it'll definitely be good for your E6550
just be sure to put 1 or 2 120mm fans on it. It doesn't cool nearly as well without a fan.