How to Reinstall OS using restore disc on Mac

I am using MAC OS installed on my Mini computer, it is being infected with some kind of persistent malware. When I boot from the Install Disc 1, I get the window where I need to choose a language, then a "preparing installation" message, followed by an "Alert This software cannot be installed on this computer" message. I have checked the same for atleast 2-3 times with the specification against the OS X version I am trying to install and it seems to match up from everything I've been able to read. Can anyone here suggest me how do i Reinstall my OS using restore disc.

thanks in Advance

To restore your operating system (OS), you do not have to reformat your hard drive. You can reinstall the OS from the images directory, directory located on the controller's hard drive (C:\images). So i will suggest you to search for the image in the image directory, once you get this then you just need to backup you system, and run that image file, this will save your time as well as effort.

The Restore discs included with some computers that ship with Mac OS X 10.2, This includes the Power Mac G4, the restore process of each model varies slightly.

Follow the following steps:

1. The restore is customizable. You can choose to restore all items, or select just Mac OS 9.2.2 or specific applications such as iDVD.
   
2. The Restore discs are not startup discs. Using the Restore program requires that you start up the computer from a hard disk that has Mac OS X 10.2 or later installed on it.
   
3. Because the Restore discs are not startup discs, an erase and restore requires an additional step.
   
4. Some computers share the same restore process but ship with a combined Software Install and Restore disc contained on a single DVD-ROM or multiple DVDs instead of two or more CD-ROM discs. The Install and Restore disc is a startup discs. (In the case of multiple restore DVDs, the first disc is the startup disc.)

Sorce: Apple