With an older Dell case (as reported previously) you might:
1. Have an underpowered power supply
2. Not have brackets for extra HDD's, CD-DVD drives, or even a floppy
What you might want to do is salvage the DVD-CD ROM drive and maybe the HDD (probably small GB capacity) for later use. Cases are cheap and the memory on the old Dell MoBo is so out-of-date as to be virtually useless.
You _could_ make it into an underpowered machine for the kids - that's about it.