allways a good idea.
use the solidworks rx tool to do it. ( under programs, solidworks)
Download and install a program called CCleaner from http://www.ccleaner.com/
It can be set to clean all temp files upon boot up.
Becareful using CCleaner. It is a good tool for cleaning temp files. However, if used to clean out activeX files from the system registry, it can remove some of the SolidWorks system files and cause stability problems.
Otherwise, CCleaner is a useful tool as long as it is used with caution.
Here is a great link to an FAQ on eng-tips regarding this topic.
I have been using this method for years now. SW RX may do a similar job, but this is good. The gist is that you create a .bat file to clear out your temp folders. You can then set you computer to run the .bat upon startup.
This is what my .bat file looks like: (the name of the file is Clean_SW_TEMP.bat)
c:cd %USERPROFILE%\local Settingsrd /s/q Tempmd Temprd /s/q TempSWBackupDirectorymd TempSWBackupDirectory
Retrieving data ...