Trying to format power mac

[Karlfischer]

Figure I try asking here in case anyone knows:

I recently got a used power Mac (I think g4) and am having difficulty reformatting it. 

I have tried doing command + R on reboot, but nothing happens.  I am not sure what version of Mac os x I have, but I think it might be snow leapord.  In that case, I might need the install disk...which I also don't have.

I also do not know the existing user login.  So I am now with a useless machine that I can't use.  Also, macs are very foreign to me, so I'm a bit lost.

In worst case, I am considering loading linux onto it.

Any ideas?   

[btraill]

Really? It won't boot into the disk utility/recovery window? That's odd. You need to make sure you have that keypress before the apple sound makes the ding. Make sure you're using CMD and not CTRL.

Have you tried these methods? It's gonna be tough if you really can't get into the OS or to the recovery options.

http://support.apple.com/en-us/ts1417