You cannot boot from compressed files such as rar or zip. The contents of the rar files need to be extracted and then burned to disks or download the ISO's. Download ISO's from here:
http://www.mandrakelinux.com/en/ftp.php3
At bottom of that page choose "I'm already a member of the Club or plan on registering soon, please send me to the download page" and choose "Mandrakelinux 10.0 Official ISOs/i586 " on that page. When downloads are complete you will have ISO images on your hard drive, just double click on those to have a program like Nero or such burn them.
Alternatively, if you had already burned the contents or the rar's to disk, and not the rar's themselves, then maybe you have the beta version called Mandrake 10.0 Community (not official) as there was some issue of them not booting off the first cd and needing to be booted up using cd#2 or something like that.