Ok, so I'm only posting this because I had problems with booting Linux from a flash drive on some of the Dells around here (most notable a GX270 and a Precision 650). I could boot Slax and DSL just fine on most machines, but on the Dells, I got the error "Unable to load operating system". The fix for this was found on the DSL Wiki, and it dictates that you have to overwrite the MBR of the flash drive with something called ms-sys . I did this, and booting on those problem Dells became easy.