Don't expect an installation to work correctly unless you start by formatting your hard drive. You can "repair" windows if it stops working properly, but this preserves all settings including virus-altered ones. Internet Explorer also has a "repair" function.
With NTFS, you can make Program Files folders read-only for limited user accounts. By default, even limited user accounts can corrupt programs that are already installed.
Originally Posted by nmenaker
reinstall is always a good idea, every 12-18 months or so.
I totally agree. Use the recovery disk that came with your computer then install necessary updates. If you have lost the recovery disk or added components yourself, get a list of all the hardware on your computer (hardware manager will print this for you) and go to the manufacturers' websites to get updates. Copy them to a CD-ROM or USB zip disk so you'll have them after the XP installation.
Originally Posted by nmenaker
much of the crap comes in in IE or other browsers, or even in emails and I don't think installs as an application.
Occasionally, you have the problem of virus scanning software not being able to remove a file that is in use, or sometimes a virus was installed as an administrator and you can't remove it. In this case, it is helpful to start the computer in safe mode using a different account than the one which was having the problems. Password-protecting the administrator account is a must.