I guess the problem was the way I burned the CD. I tried it again by buring the "disc image" (instead of all the files separately) and the CD boots up fine. It's curious, because all the same files are on the CD and one works, but the other doesn't.
I have the same problem as Jeff. I can boot from a 32bit XP CD but not from a 64bit CD. And I have PentiumD 945 processor. It seems if there were an x64 bootdisk set, then it would work.