It sounds as if it has a Hardware issue so even wiping the HDD may not be possible. However if this just started after you attempted to install from the MAC Install Disc it is most likely a software problem.
To diagnose a Hardware issue get a copy of the Ultimate Boot CD from here to test the Hardware
http://www.ultimatebootcd.com/download.html
If it's software related you may very well find that your Mac install Disc doesn't support the Hardware that is in the Dell. MAC OSX has a very limited Hardware Base as Apple [b]Do Not[/b] use a open system but a locked system so that they retain complete control over things. For this reason many PC's hardware Are Not supported by the MAC install Disc.
However as OSX is based on the OS BSD you can use Open BSD to load this PC and install whatever Mac Software you require. You can download a copy of Open BSD from here
http://www.openbsd.org/ftp.html
Boot & Nuke will wipe the existing Partitions on the HDD and Autonuke should be sufficient unless you want a complete destruction for ever on the HDD. By using Autonuke this will wipe the HDD and leave it blank and like a new HDD to partition up and use.
Col