Use the Restoration Disk.
Perform a Repair if you are going to keep existing personal information.
(i.e., Documents you have created or downloaded, Photos, Music, and programs you have downloaded, or installed)
Repair is a Non-Destructive Installation.
Perform a Full Installation if you do not plan on keeping personal information.
Full Installation is a Destructive Installation.
If you do not have the Restoration Disk for your Compaq Armada E500, you can obtain it from HP Support. (HP owns Compaq)
In the USA the Restoration Disk is free.
The shipping and handling is not.
$17 for a 5 to 7 day ship, $24 for a 2 to 3 day ship.
(24hrs a day, 7 days a week)
For all other countries please click on this link,http://www8.hp.com/us/en/hp-information/summary/ww-support.html
If you format the harddrive the wrong way, you will wipe off the Windows operating system.
You'll have a blank harddrive.