Hi,
You may need to contact Dell support as to the capabilities of the disk you have. Depending on the manufacturer, a recovery disk may have options to just reinstall, backup and reinstall, wipe and reload to factory state, etc. A manufacturer's recovery methods differ greatly from a normal Vista install, and even from other system builders, so Dell support is really where you should be asking these questions.
Reinsert the disk and see what options you are presented with to begin with.
Best of Luck, Rick Rogers, aka "Nutcase" - Microsoft MVP http://mvp.support.microsoft.com Windows help - www.rickrogers.org