Like homes and cars; computers need to be checked over, cleaned out, and tuned up once or twice a year.
Your computer will be happy if you take care of it. PC Tune-up is a maintenance that should be performed
regularly, this helps the computer run faster smoother by freeing those unnecessary used resources.
 

Uninstall Unused Programs

Computer programs installed on the computer are using resources, such as space, memory and CPU.
Have you checked if there is any program that you don't need any more? All brand name computers comes super loaded with trial software.
Even those computer programs you have paid for such as the anti virus, just because they have expired doesn't mean they go away. If the antivirus program has expired, they are not protecting any more.

For a list of all the software on your computer that has an uninstall program, select:

For Windows XP => Start, Settings, Control Panel and double-click on Add/Remove Programs.

For Windows Vista default Desktop => Start, control panel, classic view, Programs and Features.

For Windows 7 Default Desktop => Start, control panel, view by- Large icon, Programs and Features.

Some applications listed may be obvious and yo can easily uninstall them, others may not be so obvious.
If you are not sure which one you need and which one you don't, then it will be better if you consult someone who knows.