Did you even try installing the latest version of Microsoft Windows
Installer, v3.0 that I gave you the link for?
Well, ok, that gets you going but millions of people now are using SP2
without problem, and almost surely quite a few with the same brand and model
that you use. It is very important that the system be known to be clear of
all virus, adware, and so on before SP2 gets applied. The system should be
operating pristine before applying SP2 (not that the observation is of
benefits if SP2 was installed as part of automatic updates!) It is also
important to apply a fix before upgrading to SP2 if you use TV Media.
Something else is wrong if SP2 won't work with your computer. Pay attention
to your event logs, and if using XP Pro then enable auditing for all
failures. I'd say SP2 is the victim, rather than the problem, and backing up
might be a good thing. You are at security risk on the internet much more so
without SP2 than with it.