Originally posted by Conan
I just recently tinkered with my friend's Compaq notebook. First I formatted the disk, then waited for a DOS prompt to install Windows Me, but alas no DOS prompt appeared. So we took his restore CD, rebooted with it and it started to restore his O.S. to the original Windows Millenium.
Conan is right. Most recovery disks are bootable. They restore the computer to the way it was when it came out of the box.
This usually includes Windows and some other software (such as Word Processing or Anti Virus - if it orginally came with your PC )
A serial number is usually NOT required.

BTW - Most of the time PCs with recovery disks are set to boot from the CD-ROM drive by default - but sometimes it may have to be enabled in the BIOS.
Just a tip!