Step 1. Make a folder called Registry backups.

Step 2. Go to Start and type regedit

Step 3  Click on Registry scroll down then click on Export

Step 4  In file name, go to the back up folder and name your file with the date (example... regebackup-10-26-01).  That way when you restore it you simply click on the last known good back-up you created and say yes to the prompt.  

notes:

The official site says to save it on your desktop but says to delete it because you can accidentally click on it and change your registry to an old one and none of your new programs will work.  Don't worry because you will be prompted with a warning before that happens.  Just put it away in the folder you created just to be extra safe.

Notes: (more babbeling)

Simple easy and safe.  If you suspect your registry is messed up you can temporarily save it by the method above and install (import a registry file saved under a different name)  the latest backup.  If that takes care of the problem then you saved your computer.  Plus you still have the option of reinstalling the back-up you just made. 

I make a back up (export under a different name) before I install a new major program or about once a month which ever comes first.  I make a back up after I install a major program and know it's working well.  I also make a back up when I start having lots of computer crashes or a few days afterwards if the problem has mysteriously fixed it's self.  To date I've saved all my back ups... but you may want to delete them for hard drive space as they are huge files.  Since I have 40 gigs I don't worry about it.  

*WHAT IS A REGISTRY ANYWAY?

 If your registry file gets corrupted windows wont work and you will have to reinstall it.  Usually you can get it to come up at least once after several tries... At that point I install my latest back up.  I've never had to reinstall windows to get it to come up or use a back up disk... but If I do I have the option of installing one of my back ups later.  *The registry file is the file windows uses to keep track of what programs are on your computer and how they relate to windows.  Every time you install or modify a program it puts instructions on the registry file to use the program.  Without these instructions your programs wont work.