52 Celcius really isn't that bad at all for that chip under load. My XP chip runs at ~66C during the summer months under load, and I've never had an issue with it. It's 'trendy' to have high-end cooling these days and CPU temps in the 30's-40's under load, but I don't think it really makes that much of a difference. Some may say it lowers the lifespan of the CPU if it runs hot. Perhaps so, but you'll upgrade long long before it ever fails at 52 C.
The FX series CPU's runs especially hot with the retail HSF, they hit 60 C easy and are rated for about 80 C max. In my opinion, aftermarket HSF's are a luxury. (Well, unless you're going for max OC or using a Prescott

) Sure they're nice to have, but not necessary. I'm assuming from your idle temps you have an aftermarket HSF.
If your system is stable now, I really wouldn't start to worry unless it breaks 60-65 C. Even then it'll probably be ok.