Another possibility is to put the hard drive into an external case and use the firewire or USB 2.0 port.  Try www.dealsonic.com for a reasonably priced external enclosure.

You cannot keep both optical drives and install the EIDE drive without purchasing additional hardware. You'll need either a PCI EIDE controller card, or a PATA drive to SATA controller converter board.

Thanks ejn63.  So you are saying if I buy a PCI EIDE controller, it should work.  Have you even done that?  Where can I get a PATA drive to SATA controller converter board?  If both solutions work, which one you suggest?  (buy a new controller or converter).  Thanks a lot.

The EIDE controller method, with a good (Promise) board will work.

The SATA converter method is less likely to work, because of the variable quality of these converters. I've seen them work in some cases, but fail in others, not just with Dells, but in other systems.

If you decide to try a converter, here is what you need:

http://www.newegg.com/app/viewProductDesc.asp?description=12-107-112&depa=0

If you have firewire, I recommend getting a case with firewire connectivity.  It's faster than USB 2.0 in real world scenarios.  There are several cases available with both firewire and USB 2.0, if you think you might need to connect to a different PC.

Good luck!

Thank you all for the suggestion.  The external enclosure sounds like a good idea.