If your computer is getting slower and slower and is younger than 5 years old, the odds are that you don't need to buy a new computer in order to speed things up.  Computers are like gardens.  Every once in awhile you need to go out and pull up the weeds.     With this in mind,  there are five simple things that you can do to speed up your computer.

1. Check to see how much RAM your computer is equipped with.  The easiest way is to right click on your "My Computer" icon and select "Properties".  You should see something like this.  Notice that this computer has 3 GB of RAM, which is nearly the maximum amount that can be accessed by a 32 bit operating system like Windows XP.    I'll bet that if your computer is older than 2 years, you'll only have 256 MB of RAM.  This really slows your computer down.   In order to upgrade, you'll need to determine what kind of RAM your computer actually uses.  In most cases, this will be either DDR or DDR2 RAM.   Either of which, you can sometimes find at Walmart or your local computer repair shop.   You can use the free online scanner at Crucial.Com to determine the type of RAM that you computer has.  Once you have this information, you can order it directly from Crucial or your local dealer.
2. Clear out your junk and temporary files on your hard drive.  I have found a free program called CCleaner that can be used to clear out most of the hidden and unneeded files from your hard drive.   It will also clear out your cookies and erase your surfing history.     I recommend that you run this program at least once or twice per month, if not more.
   
   
3. You may want to try defragmenting your hard drive as well.  This will speed up your computer's access to the files on your hard drive.     Windows XP and Vista come from the factory with a free program that will defragment your hard drive.  Simply go to your DOS prompt, by clicking the Start button and typing "CMD" in the  "Open:" box.  Then, click "OK".    When the black console screen is displayed, simply type the following command, followed by the Enter key to defragment your C drive. This may take up to an hour or more to complete, so be patient.  It may be best to run this command at night before you go to bed.

   defrag -v c:
   
   

   I also recommend a program called Defraggler.   It's made by the same people who wrote CCleaner.
4. Uninstall  dead weight.  Older versions of Norton Antivirus and McAfee Antivirus should be uninstalled.  Simply go to your Control Panel and click on Add/Remove Programs.   Then, remove these programs and install a free antivirus program like Microsoft's Security Essentials, or Avast. These programs are slimmer and do not tax your computer as much as the older bloated antivirus programs.
5. Don't install junk!  Be careful what programs you install on your computer.  File sharing programs that your kids use to download music can be tempting to install, but they always bring problems such as spyware or even viruses that use your computer to spew out Spam and other viruses.
   
   Remove any programs that promise to speed up your computer or increase your RAM.  In most cases, this programs will, instead, slow down your computer to a crawl!
   
   Get rid of all of your Internet Explorer tool bars.  Do you really need a Google, Yahoo and Ask toolbar cluttering up your screen?  The answer is no.  In fact, you can probably get by without installing any toolbars.