Before using any of those so-called 'fix it' programs, you make sure that the usual reasons for a slow PC are not affecting your's..
Like not enough RAM? One or two programs are hogging the RAM? A 'bloated' Registry full of junk entries? Your HD needs defragging? Your HD is nearing capacity?
If the paging file is too small it can cause the machine to 'pause' [appear to freeze for a minute or more] while it sorts itself out. That happened to my new m/c running Vista until I ramped up the file to maximum.
There are several reasons for running slow so try some sites for help:http://www.howtogeek.com/http://www.techguy.org/