I started out on a 4850 months ago, but only ran it for a couple days. It was prone to overheating, and having the fan screaming at 100% was not my cup of tea. When I took a second look at Bitcoin about a month ago, I had just built my new computer with a 6950. That quickly grew to two unlocked 6950s, and a second rig with a 5830 and the original 4850 offsite. Thankfully I've broken even, but I understand your pain.
Really?
Mine has had no problem staying cool.
Albeit my case is covered in fans, the fan rarely turns on, if ever, and generally stays at about 74 celsius.
I'm about to starting teaching a few people how to play instruments, so i'll be having enough money coming in to get a better MOBO (like one with more than one PCI-E x16), and then better cards.
Best part is, this is all stuff I was planning on doing before I found Bitcoin.