jack2009

They both have their own boot sector. The easiest way to do that would be to use something like UBCD - and it seems you're already aware that it's not really worth the hassle to do that. Even easier still would be to just burn them to seperate discs, as Brandito suggested.

They're probably better (more reliable) on their own anyway. Eliminates potential glitches in whatever software you use to boot them together, which is pretty much the main reason they're not designed to run in Windows.