g5 lock screen

[countryroast]

I got my first ever mac (power mac g5) at an auction. when i power it up i get a picture of a lock and a place to enter a password. What is this and is there a way to get past it? i did pull the hdd and used mac drive on my windows machine to check the drive for errors.(none found) it appears to have leopard on it. any help would be great. if you you need more info,i will do my best.
i am not familiar with macs..so please forgive my ignorance.
Thanks!

 

[countryroast]

got it done!!!
did this....
Bypass Mac Firmware Password

and this...
Forgot Mac Password? How to Reset Your Mac Password (with or without CD)

hope this helps any one else with the same problem.