The question I'm asked most frequently is, "How can I speed up my PC, which has gotten much slower over time?" Although I have detailed instructions on my site, several readers have asked to have them posted here.

One of the main things that slows down a PC is having unnecessary programs running in the background. They drain resources and slow down the programs you want to use. The culprits can be found by clicking Start>Run, typing MSCONFIG, clicking OK, and then clicking on the Startup tab that appears.

Here you will find a list of programs with check boxes. Many, if not most, will have a checkmark, indicating the programs have been told to start running when your computer is turned on. Why? Well, the theory is that having them running constantly means you will save a few seconds of "startup time" if you decided to use them. This is like having your car parked with the engine running all day so you can save a few seconds when you decide to drive somewhere.

Some of the usual suspects in this list are AOL, RealPlayer, AIM, Adobe Reader, and MSMsgs (Microsoft Messenger). Unchecking these items does not delete anything, it simply tells them not to run until you want them to.

Your onboard anti-virus program, however, should be on all the time for maximum protection. The only other program I have checked is Yellow Stickies because I use it so often and because it is a small program that uses few resources.

If you uncheck a program and later decide you do want it run at startup time, repeat the above steps and recheck the item.

Another thing that can slow down a PC is disk defragmentation. Data added to a hard drive are usually done sequentially, which makes it easier to find later on. However, when files are moved around or deleted the disk becomes fragmented. This can be fixed by clicking Start>My Computer, and right-clicking Local Disk C:, and choosing Properties.

Click on the Tools tab and you will find Defragment. Click this option and follow the simple prompts.

Also under Tools you will find Check Now (in WinXP) or ScanDisk in earlier versions of Windows. On pre-WinXP computers, ScanDisk should be run before running Defrag. Check Now can be run at any time in WinXP. Check Now (a.k.a ChkDsk) and ScanDisk both examine your hard drive for disk errors, and are usually able to fix any problems they find.

Another option under Properties is Disk Cleanup, which should be run along with Defrag and ChkDsk.

Another source of computer slow-down is spyware, which is usually acquired by visiting dubious Web sites. Defender is a free anti-spyware program available at www.microsoft.com. I prefer Ad-Aware, a free program whose link is on my site. Many folks use both programs, since no one program can guarantee to find all malware all the time. However, both programs have free updates that constantly look for the latest threats.

More on PC slow-down at www.pcdon.com, and calls are welcome at (949) 646-8615.