XP reinstall, not original recovery disk

Hi.  I work at a non-profit and ome of the things we do is redo old pcs to give away to people with disabilities.  I am working on setting up an old machine (Dimension 4600) to give away.  I wiped the harddrive with Darik's Boot and Nuke (www.dban.org) and am trying to reinstall XP from a disk that I know did not come with the machine and I can't get that anyway.  The machine has been upgraded RAM-wise (to 1 GB) so a lack of RAM is not the problem. When I boot the pc with the XP installation disk in it, the light on the cd drive flashes but the cd doesn't start.  I have set the BIOS to boot from the cd but that doesn't change anything.  The cd works when I put it in another Dell machine that is running Win XP.

Any help is appreciated.

Tony