You can download and scan your PC for free.

However, just because your computer is running slow does not necessarily always point to some sort of malicious virus or spyware. Normally, it has to do with your settings in your computer. Lots of programs, by default, start when you begin Windows. If your computer freezes or runs extremely slow as you start Windows, this could be your problem (debugging messages and run-time errors are often the result of far too many programs running in the background).

If you’re running XP, hopefully you are, go to start>Programs>Start Menu and just see how many programs are there. Remove all of the unnecessary programs that you don’t want in there (Right-click and select delete). This will only delete the shortcuts, and thus will not affect the program itself (you’ll be able to run it later if you choose to through the start menu). Then restart your computer.

Once you get into windows, hit CTRL + ALT + DEL to pull up the Task Manager. Click on the Processes tab and click on the column that says User Name. This will sort them by User Name. Find the section that does not have the user name of SYSTEM, LOCAL SERVICE, or NETWORK SERVICE, but rather the name of your computer. This will show you how many programs you are running, whether or not they show up on the Task Bar.

You can choose, at this point, to try to determine which programs belong to who and go in manually to turn of the “run at start” option. This is totally up to you and your competance with computers. I suggest every time you restart your computer, go into the Task Manager and end the processes in which you do not need (You need “explorer.exe” and “taskmanager.exe” within your computer name). This is the easiest and most efficient way to speed up your computer.