Your download file should been about 688MB. Was it? And, that would fit on a CD. Of course, DVD could be used but CD can also be used. So, if you tried to burn the ISO to DVD and got a error message saying "short 120MB of space", you made some mistake somewhere in this whole process.
Again, do you have an ISO file of about 688MB? If so, I would try burning again. I like the ImgBurn program that BC_Programmer mentioned. It's freeware and works well for creating bootable discs.