If you are like a lot of people, you notice that your Windows machine becomes slower over time. This is due to your constant install and uninstall, include the multiple updates that your softwares get. Even if you don't install new software, you find that your Win machine grows slower over time. You install a cleaner program like CCleaner, and sometimes it improves your system by removing orphaned and unnecessary programs from your system, but if you are not careful, you might break your system if you remove a needed dll, for example. Sometimes, the only way to ultimately clean your system is to do a full reinstall of WinXP.
Installing WinXP is not really that difficult, but it does take a lot of preparation and a LOT of time. First, you have to back up all your personal data away, if you have a lot of data, this may take from several hours to several days. Next would be to prepare all your install disks before doing anything, and this includes your WinXP setup disks, Hardware drivers, Printer Drivers, Video Drivers, DVD drivers, Office programs, Printer Programs, Scanner Program. By preparing all of these disk ahead of time, will actually save you time in the install process. So now take away one (1) weekend of your life to install WinXP and all your programs, update, tweak your system to your desired settings. Now you have a system working at it's peak at the moment, but you know that in three (3) months or so your system will degrade and you will do this all over again.
So how can you avoid this very tedious process. Microsoft actually has a free tool that will help you keep your system at its current level everytime you boot up. Microsoft Steadystate will actually freeze your system to it's current state, and even disallows your users from writing to your system drive. Once set, anything that you install or write to your C: drive will be erased and removed upon boot up.
How about your personal data, well, when you reinstall XP, it is a good idea to par***ion your drive to separate your system and programs and your personal data, a drive C: and a drive D:. Since Microsoft by default installs 'documents and Settings' to the system drive (C:\), you need to tweak the system to be able to move your 'documents and Settings' to drive D:, otherwise anything you save will go away after a reboot.
I like Microsoft Steadystate in maintaining my Win XP machine in a steady state. So if you don't really change your settings that much, Microsoft Steadystate is a good way to keep your system constantly healthy and well ... steady.