After awhile, your computer can slow down even if you've been doing the same things with your computer.  The three steps below will get your computer running faster and more efficiently.  These steps are for Windows PCs and not Macs (they have their own procedures.)  Here they are:

1. Delete Temporary Files.  The computer accumulates temporary files as various programs are run, and these temporary files do not disappear when you close the program or turn off your computer.  There are Temp folders under each user profile, as well as in the Windows folder.  Any files in those Temp folders that can be deleted, should be deleted.  If you can't delete a file, that's OK because the file is being used.
2. Clean the Windows Registry. The Windows Registry is a set of files on your computer, like a database, that stores configuration settings and options on Windows and all the programs.  When you install or update a program, that program adds information to the Windows Registry.  When you delete that program, the information may not be deleted from the Registry.  CCleaner is a free program from www.ccleaner.com.  It will safely remove unnecessary Registry entries, as well as delete temporary files from other locations on your computer. 
3. Defragment the hard drive.  As you use the computer, the files on the computer may be split into multiple fragments throughout the hard drive.  This is a very efficient storage method, but lots of fragments can slow down your computer.  The defragmenting process recombines the files and removes the fragments.  The Disk Defragmenter program is a part of Windows, and is necessary only in Windows XP and Vista; Windows 7 does a good job of automatically defragmenting on its own.

That's all there is to it.  If you have any questions or problems, please let me know.  If you'd rather we come out and take care of this for you, we would be delighted.  While these are the first three steps we follow when cleaning a computer, we have a total of about 20 steps depending upon your computer configuration.  We support small businesses, home businesses and home computer users in the Greater Houston area.  Just call Clerc Computer Consulting at 713-861-4183.  We will save you time, headaches, and a whole lot of frustration.