Yes, it could be any of the issues mentioned in the article, especially heat. Try simply setting a portable fan to help cool your machine. If it has never been cleaned inside, that's a good idea too. Get a can of compressed air and blow out the dust. Gently hold the fans so they don't spin. You could damage the bearings. On the software side of things, check to see how many background processes you have running. Asking Windows to do too much all the time often means that one more request is just too much. Many programs set themselves (and/or their updaters) to start with Windows. This means that they are always there, working in the background. A free program like WinPatrol or What's Running offers easy control over that sort of thing. You have a startup folder under all programs. How many items can be just started when you need them and don't have to start with Windows? Have you ever been to "Services?" Made any changes there? Some are very necessary to the average user and some are not. The default settings of Services for XP are good, but depending on your needs you may not need all of them all of the time. You may wish to set some to "Manual" so that they start only when needed. Before making changes to Services (found under Administrative Tools) please read: http://www.theeldergeek.com/services_guide.htm
Yes there is a lot of information there. I suggest that you bookmark it and refer back as you work. The best plan is to make changes there one-at-a-time so that you know what "broke it." Sysinternals makes a good free utility called Process Explorer that will help. A mouse-over a listing of "scvhost" will pop up a small info box with the Services it is hosting.
No need to install, just run it from wherever you'd like to put it. (double click the .exe) If these sort of things help, you're probably on the right track. I'm assuming that you have good security and firewall and are not hosting spyware. That is often the root cause of this sort of problem. If you suspect for any reason that your system is infected go directly to the "Security" section and follow the excellent advice that you will find there. Good luck and post back with your progress.