you can set one in the bios. check your manual, or just play around, it should be pretty easy to find the settings. Usually you can set it up in one of 3 ways. 1. disabled. No password set.(default) 2. Setup. The system will boot without a password, but you need one to enter the bios and make changes. 3. Startup. You need to enter a password to boot the computer. The only way around this is to erase/flash the bios. For XP you can go into the Control Panel->User accounts. open your account and then click 'create password'. Be sure and add a password to all accounts on the machine or disable them. The advantage of the Bios method is that the system doesn't even boot unless you enter the password. The advantage of the XP method is you can lock down the machine without turning it off, or even logging out(winkey+L). Of course you can do both, if you don't mind entering a password twice at bootup.