|The Essential series is pretty old. It would help to know which model, but I believe they were Win98 machines. Does it have at least 512MB RAM? If not, you're more than likely wasting your time trying to install XP on it.|
We have no idea what password it's asking for. It may be the BIOS password but it shouldn't automatically pop up without a specific key being pressed. Have you opened the case yet? If not, unplug the power cord, open the case, then temporarily unplug the power & data cables from the hard drive. While the case is open, clean out all the dust bunnies. Once you've done that, boot the system & see if you're still hit with the password prompt. Obviously it won't boot into Windows without the drive being attached, this is just a temporary test to try to identify what password you're being asked for.