well, as far as the hardware issue goes, I don't find any problem with the size and power consumtion. I am working on a similar project, only difference is that it is for a different task of talking out books. there are very small size embedded boareds with built in processors and ram and sound/ display cards. the bios supports booting from a compact flash card or a usb pen drive. I will grab the small embedded computer board in next fort night. I will let you know how it goes. the idea is good and right now even I am trying to build a kernel that will only have essential modules to boot off a pen drive along with usb support and sound card support. when I get it working I will let every one interested know. I am aware that it is not too difficult but it is not too easy when it comes to implementing the same os on a usb device. I am not going to use any ready made os like slax or puppy linux. for such tasks one needs to compile their own kernel.