moist

Can anyone please help me. My computer is running slower. I have installed and un-installed many sofware ... could it be the problem? There is no virus..... someone suggested that cleanng the registry will solve my problem but I don't know how and I'm affraid that if i tinker with the registry, it might damage my system. I don't want to re-format my drive or run a system restore cause I have important files in my drive... please anyone???