Wiping HD except osx
Hey all. Long story short I'm trying to wipe out pretty much all the junk on my sister's old lapetop that's the same as mine Powerbook g4 15 in. I had a HD failure and want to use her laptop temporarily to save all my photos online.( I have many time machine backups that I can restore from, just not enough free space) The HD is practically full but there really isnt much on it ( 150 pictures, maybe 150 songs, ect.) and of course osx 10.5.8. Is there a way to wipe everything off the internal HD except the os? Her optical drive is broken, and I have an external one. I tried booting from the disk but it just wouldn't let me. I'm afraid if I wipe out EVERYTHINg I wont be able to reload leopard. Thanks!
PowerBook, Mac OS X (10.5.8), 1.5 GHz PowerPC G4