run once per week a junk and registry cleaner

ccleaner is the best solution and is freeware

http://www.ccleaner.com/


ps: every time i run this i delete 1GB of junk and temp files from web and windows aplications (yes im a harcored user... my computers never sleep LOL )

for mac use MainMenu also freeware

by the way try to not use shareware aplications , the freeware solutions beat them all , somethimes are runned by open source comunities and updated every week