What version of Windows are you using and is it 32-or 64-bit?
After you removed the bad module, did it boot properly? Did you try swapping pairs of modules into each other's slot to make sure it's a module problem rather than a motherboard problem? Always power off, unplug and press/hold power button for ~15 sec before working inside the case.
Why are you trying to "restore"?
How are you trying to restore, Windows System Restore or Dell's PC Restore? Are you seeing any error messages? What do you see on the screen?
How many RAM modules do you have now, including the bad one? You need to replace RAM in matched pairs, so you're going to need to buy 2 matched modules at minimum. Be sure to follow the instructions to replace the RAM modules that starts on page 22, here.
Many people around this forum buy RAM from Crucial because they guarantee it works in the Dell for which it was bought and they have decent prices. If you have 64-bit Windows, you can use up to 16 GB of RAM (4x4 GB). You can buy 2x4GB for $70, so 16 GB will cost $140.
(I'm not that far from Berkeley, since I'm in the Bay Area too!) 