Is there a "universal" way of how you can make a bootable USB drive out of a bootable dvd or cd? What makes a USB drive bootable? What makes a dvd and cd bootable?

For example there is a program called UNetBootin which can make bootable USB drives, but seems like it only works with various linux distributions. (Tried it with a Win7 image and the SystemRescueCD, which didn't work so well...).

Main reason I ask is that I have a Support DVD which came with an Asus EEE, and it of course doesn't have an external dvd drive. So I am curious if I can sort of move that dvd over to a USB drive so that I can use it without buying one.

Not asking just specifically about this one case though, I am curious to know a bit more about this in general. So, if you have a general bootable DVD or CD (Or a DVD or CD image for that matter), could be linux distro, windows install disk, support disks, etc., is it possible to "move" it over to a USB drive and make that work like the DVD or CD did? (Being bootable and all).