Dell XPS/Dimensions 600 Installation of OS unable to be completed

I had to reformat my mother's computer because of several virus' she had that continually blocked her ability to connect to the internet. After several removals of virus' and several attempts to correct the problem, I decided to reformat. I f-disked the computer, then realized that there was a problem with the raid card and the hard drive being recognized when I went to do a fresh install of Windows XP. I am not sure exactly what is happening, but it says there is no recognized hard drive and now I have a computer case that cost a lot of money...but is nothing more than a paperweight. She thinks it is something I have done, but in reality, I really didn't do anything different than I have ever done when reformatting. It appears that Dell computers are a lot different than other computers...the raid card being one of the huge differences. I not hugely familar with raid..therefore I need someone to explain what it is that I may need to change to allow the hard drive to be recognized. Thanks for any help you can give me.

As I continued to try different processes, I decided it might be good to post the messages I get. This is the message when I put in the XP disk and reboot:

:setupdd.sys Page_fault_in_nonpaged_area ***stop:0x00000050 (oxe50f5098,ox00000000,oxf74249a8,0x00000002 ***setupdd.sys-addressf74249a8 base at f73f0000,datestamp 4110708f

If I don't use any disk and go to reboot, I get the message: detecting array... 0healthy nvidia stripe 149.01G ctrl-n enter raid setup utility

If I pressed ctrl-n, it does nothing.