Older systems may benefit from a bios update but don't rush into that yet. As for memory, more than likely 512mb stick is too much for that older systems, probably 256mb per slot is it. However, you should check the Dell support website for details/specs on that model system. Use the serial to proceed or just the model number, once to get the proper page, review it. You can also get the bios update for later action, but not now, at least make the system work before doing that and *save* the old bios data when prompted and have a good floppy ready for all this. Of course check all cabling, pin-1 to pin-1 ordination, master/slave setup, older bios reflects that, maybe battery status(old battery) and take 1-step at a time until it boots and shows, OK.

good luck -----Willy ":)"