At W2K startup, try signing in using the word "administrator" (w/o quotes of course) and the same password you are currently using. There is at least *some* chance that your buddy used the same password for "user", "power user", and "administrator". Normally you should be logged in as either "user" or "power user" rather than "administrator". This is particularly true if you are connected to a network, including the Internet.
Some programs are to be run as "administrator" only. However those programs can be run while logged in as "user" or "power user" by using the "shift" key and then *Right clicking* on the program's icon. This will open a dialog box which will give you the option: "run as",at that point simply type in the word "administrator" and password and the program will run. This is assuming that your friend did not change the default name (administrator), and the password is the same as the one you normally use.