None, that's funny that SP2 has given you problems... (not funny haha, funny.. well you know what I mean)
I don't really want to install it either, because of the posibility of a problem. For now, this computer does everything I want it to, and I don't want to screw anything up, for something I didn't really need in the first place. I'll definitely install SP2 eventually, but not yet.
There is actually a thread here about SP2, and it's a poll asking how many people have had problems with it. There are a HUGE number more of successful installs, over ones that caused problems.