Secure erase of system drive prior to donation?

My wife just replaced her old PowerMac G4 with a MacBook and I'm planning to donate the G4 to a local charity. She was running OS 10.4 but I only have install CDs for 10.2 since the upgrade was done as a download. I've used Secure Trash Removal to clean it up as much as I can, but would like to do a secure wipe of the system drive and then reload 10.2 before I give it away. But 10.2 off the CD doesn't support the Secure Erase. I've downloaded Permanent Eraser but not sure if I can run that from a CD to wipe the system drive. What is the best way to proceed? (hope this isn't a dumb question - I'm a PC guy so I'm not familiar with all the Mac tricks. Her G4 was used for her business, so I really want to wipe it before it goes out the door.
Thanks in advance!!
Tim

You can run the mac of the restore disk by pressing the C key on strat-up

From the intsall screen, select Disk Utility from the Utilities menu, you can erase the disk from there before continuing on to a fresh install

True, but the erase function in 10.2 only erases the disk index, not the actaul file data. I was looking for a way to perform a secure erase that deletes or overwrites the actaul file data, otherwise it can still be recovered.

Your best bet then is to trash everything but the essential files. Then copy a large amount of data (say a collection of MP3s to near fill up the drive. Then trash them, do that as many times as you wish, all that overwriting will kill any chance of the original files being rescued. Or you could use disk utility to write a disk image to fill up the space

Then you can do a fresh install knowing that files have already overwritten the original data