You can look it up but with Knoppix STD there is a program that allows you to set NT passwords. Knoppix is a flavor of linux that boots from the cd and does not install to your hardrive.
If you want to reset the password there is a program called chntpw in Knoppix STD that can do that for you
This link will show you how to actually figure out what the passord is

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Both work well just depending on what you need