How to reinstall XP

It takes a LONG time...

Do you really want to do this?

Well first, you have to check if you still have that Windows XP installation CD... if you don't...

then...

I don't think you can do it.

There are some performance tweakers crawling all over the place though if that's what you're looking for.

If you have it, you obviously have to save all your important stuff on your drive or a cd first.

Then just boot from the XP installation CD and there's a wizard that you configure and should do the rest. At the beginning it'll show a partitioning menu before the wizard.

Sorry to state the obvious but have you defragged and ran reg and system cleaners?

Windows XP installation instructions. I have done this and it is WAY, WAY too complicated to be advised here. There are drivers to be backed up, that
aren't included in a typical Windows install disk (If this is what you have). A system restore disk included with your p.c. may have the drivers, but it's best to back-up EVERYTHING just in case. I speak from experience, this is nothing to take lightly, if you want to get your system back up and running. You may even want to consider the services of an expert p.c. repair tech. Try HorusofOz's advise first though, that might help you out.

And to prove that point, I intentionally hosed my system when I moved in with my wife (before we were married) and made her reinstall Windows. Granted it took some guidance, but more often than not my answer was "well what do YOU think?". And if my wife can do it, someone who knows about PortableApps can probably get it done.

What you need:
1. Windows XP CD and CD Key. The key will be on your PC if it came with Windows; otherwise on your Certificate of Authenticity if you bought XP after.
2. Drivers. In a pinch you could just burn your \Windows folder to a DVD-R/+R and call it a day, but ideally you should have clean drivers.
3. Applications. When you reinstall you will be left with nothing.
4. A backup solution. If you keep all your music, pictures, documents, and video on your C drive, move them to another drive, burn them on DVDs (-ROM), or put them on a flash drive.

What you do:
1. Drop the Windows CD in your computer and restart. When it asks to boot from the CD hit Enter or whatever.
2. Accept the license agreement.
3. When it asks if you want to repair your Windows installation, tell it no.
4. When it asks where you want to install Windows, look for the option to delete the partition. Delete all partitions on your main hard drive. Every last one of 'em.
5. Make a new partition, the max size of your drive. Install Windows here.
6. Format NTFS. Quick, if it'll let you. Full format takes a while, at least ten minutes. Quick format takes about 30 seconds.
7. After the format it will copy the basic files every Windows installation needs, plus the installer, then it will reboot. Do not boot from CD but leave the CD in there.
8. Windows will appear to start but it's just the installer, and it's prettier than the last one. Now this will take about half an hour, but you can't just abandon it.
9. After a good amount of time, it'll ask you who you are and ask for the CD Key. Provide it. If you haven't got it - you're ****ed. No nice way to say it. You just are. This is why it's good to make sure you have a valid CD Key. There are programs that will tell you your CD key, but even if I knew more than that, we're not supposed to speak of such things up here, I imagine.
10. After a bit more it'll ask you about networking. If you're just a regular Joe, just click on through - nothing to see there.
11. After a bit longer, it'll finish. Take the CD out and reboot again.
12. Nice clean Windows. That is what Windows is supposed to look like before OEMs like HP and Dell mess it up.
13. Reinstall your drivers and apps. Restore your backups.
14. ???
15. Profit!

(Had to do it, those last two steps...)

If it's too complicated, take it to a geek. A proper geek can have you up and running before breakfast. And in less time than it would take to do all the diagnostic tools and defrags and all that. And your system will be faster anyway because it's totally reset to factory.