change or retrieve Windows password

Hi,

My neighbor just gave me a Dell Dimension XPS R350 to use as a digital video surveillance system.

When Windows first boots up, it asks for a password, and he had no idea what his deceased mother-in-law used.

Is there a way to change or retrieve a Windows password?

I also have a copy of Windows XP I could install. This would start me from scratch.

On this machine, holding down F2 does not cause the system to try to reboot from disc.

Thanks for any help you might give.

John