A common program I like to install on Windows boxes is CCleaner which cleans out your Recycle Bin, Temp files, Internet Cache and such. I have literally cleared of 2GB of temp data with this program before. I was looking for a way to run this program automatically and opted to run it at user signon.
You can download CCleaner here.
You can download the REG file or copy and paste to a new .REG file to run it automatically.
Windows Registry Editor Version 5.00 [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run] "CCleaner"="\"C:\\Program Files\\CCleaner\\CCleaner.exe\" /AUTO"
If you want to change what data is cleared you have to open ccleaner from the start menu and uncheck what you don’t want cleared. When the program is automatically run at startup it will follow the same rules.