How to _run_ Linux from a CD-ROM (CD-RW)

Can anyone point me to a way to create a bootable LINUX CD-ROM (on a CD-RW) that will allow me to run LINUX on my Gateway 300X without reformatting my hard drive? I want to be able to boot up, run a version of LINUX with an X desktop, read and write files to the CD-RW, and access the ‘net using my Ethernet card/cable modem.

I don’t really care which distribution I use, as long as its English.

Thanks.