I tryed a few programs like that, they all suck, if they did anything, they just slowed down my computer, and/or my internet connection. If you want to speed up your computer, go into BIOS, do a slight overclock (if your BIOS allows it) and other settings.
My BIOS on this computer doesn't allow overclock, however there is a setting called "Hard Disk Accustic" and there were "quiet", "normal", and "performance" i set it to performance and i really did get a good boost in the amount of time it takes to get a file.
Don't try them, they suck. (i heard that some ones $$ are really good, but the majority freeware ones suck)
just do a good hard drive defrag, and go into msconfig and find programs you don't need and disable them from starting with your computer.
a good article i found (for WinD'oh!s XP):
http://www.blackviper.com/WinXP/servicecfg.htm this guy has all kinds of good articles about small little tweaks. try to run as few programs as possible.