For several upcoming tips you're going to need to install what is called the recovery console. It has a ton of uses, that I'm going to go further into in the future. There's quite a few situations that will prevent you from getting into XP and sometimes even Safe Mode. This tool is the backup for when safe mode even fails. You can also get to any of your data without loading XP which has many uses as well. Major registry errors are probably the most common time you'll need this. You can also get to this app by booting to the XP CD.

I want to show you how to add this to your boot menu as a precaution to other things this site may show you how to do.

(X = your CD Drive)
1. Pop in the XP CD.
2. Run X:\i386\winnt32.exe /cmdcons
3. A dialog comes up saying it takes 10mb, etc., etc. - Click yes to install.

If you already see the boot menu you're done. If you don't then lets make it appear.

1. Right Click My Computer
2. Click Properties
3. Click advanced tab
4. Click startup and Recovery Settings
5. Check Time to Display List of Operating Systems
6. Set the timeout to something reasonable like 10 seconds

Apply the settings, reboot, and you should see the new option to go into the recovery console.

Here are some KB articles on how to use the recovery console and how to recover from a corrupted registry.

Corrupt Registry Recovery from MS
Install and use MS Instructions