>>4
Uhh... wrong thread genius.
Anyways, what OS did you try putting on it? What exactly do you mean "locked"?
If you have an install disk (don't use anything Dell gave you), you should be able to just clean the partition table and install from scratch during the first part of the installer. Just delete every partition, make a new one, and install.
If you just want to wipe the hard disk completely, here's what to do:
Download a Linux LiveCD (Knoppix, Ubuntu, whatever) and boot from it. Get to a terminal (command line) and type "fdisk /dev/hda" and hit enter. (If it's an SATA drive, it'll be "fdisk /dev/sda".) You should be in the fdisk program, and can hit 'm' to see a list of commands. You want to hit 'o' to get a new partition table and then 'w' to apply the changes. This will make it so you can install stuff on it like it was a brand new drive. You should be returned to a command prompt, so enter "halt" and hit enter to shutdown the machine. Then just insert an install disk and install the new OS.
Oh, and I'm going to assume you've already made backups of any important data.