nikkey

Hey,
I have an G3 iMac Snow running OS X 10.1 and am having a problem trying to boot to a CD. The CD is burned with an ISO of linux from a PC. I used roxio and selected to burn as an ISO. Is there any way to create a boot CD from a mac. I also am having a problem with my Hard Drive. My hard drive says i have 40 Gigs but only 15 is showing up as free space. When i go into the utilities menu and then hard drive utility. I am not able to format the hard drive. I tried reloading OS X 10.1 but that did not work. When i try to boot to the CD, i hold down C as the computer boots but it does not work. What can i do to fix these problems?