Computersight -

Windows will damage itself over time. It will become slower and slower and unless you assign a little time for some maintenance, you will end with a permanent crash.

To start all you need to do is to check your registry for errors with C-Cleaner.
Now all you need is to make a backup of the registry and repair it. The registry makes errors in real time so just do this once per week. More than that will not give you any significant better effect.
Don’t worry about failing. This is easy. Now you must check your system files for errors with Scan Disk. Enable the automatic error correction.
Very well. Now defrag your computer with Defragler. It’s a free software you can get from any website with downloads. Ok you must enable some automatic tasks. Make the defrag and the scan disk run every week now.
Good to see you here. Now make the C-Cleaner run automatically every week too.
The Windows hard disk cleaner misses most of the Trash.
Well done you are already here. Now you must disable the Windows Search on Windows Vista if you want some speed and you do not search very often.
You are near the finish line. Just a few more things you need to know before you are done.
Now the last thing you must do is to uninstall all the programs you do not use regularly such as for more than 60 days. Most of that software can be used online only and sometimes for free.