It's not actually decompression. That's why iso's are so large
Try booting straight off the CD.
When your comp starts up go into the BIOS and change the bootorder so that CD is first. (you can get to the BIOS by repeatedly pressing delete or F8)
******** caution... don't mess with other bios settings unless you know 100% what you are doing. They can cause the instant (or sometimes over a little time) transformation of your computer, into a very expensive desk ornament.
Once you've done that.. and it boots off the CD.. should work fine.
Could have been that the boot floppy didn't have the correct CD drivers. It's happened to me before.
Don't forget to go back into your bios and change the boot sequence back to what it was before.