I recently bought an apple g5 "2004" off craigslist. i have been able to use it just fine, well once i logged off the main user i had to reset the computer. now i don't have a password to log back on but it requires one. and we have no idea how to find out the password. also we can go on as a user, but we cant use anything. no internet, (except yahoo answers) all of our school work is saved on the main user, our pictures, music everything. please help me out if you know how to get on the main user. (oh, we also cant download any internet browser cause we dont have the right update for this computer.... 
HELP
HELP