Well, I've seen a lot of tutorials on the internet that show how to make a thumb drive bootable using Ubuntu but some of them were complicated or took too long just to make it work. This will work with about any Isolinux based distro, a few of the Slackware ones have been grumpy but can work with a little modification. Sabayon is one of my favorite distros but has problems with this hack as well, I had to use some loader files from a Gentoo live cd but it worked after that.
Anyway, here is the easiest way to get Ubuntu booting from a thumb drive using Windows XP. I haven't tried this on Vista but I'm sure it would poo-poo on trying to modify the MBR of the thumb drive. You should be able to right click on Command Prompt and say "open as Administrator" and this should work. Maybe, haven't tested it. Anyway, not pretty, just easy.
First, download a copy of Syslinux. Syslinux Very cool for making custom bootable thumb drives, lots of options only using one right now. (KISS- Keep It Simple Stupid). Unzip that sucker someplace you can remember. For example we will go with c:\syslinux so we can find it.
Extract the contents on the ISO or CD to the root of the thumb drive. This is the slowest part.
Once that is done, there should be an Isolinux folder (/isolinux) at the root of the thumbdrive. Copy the file isolinux.cfg that is in that folder to the root of the thumb drive. For our example I'll say e: is the drive. So copy e:\isolinux to e:\ and then rename it to syslinux.cfg.
Okay, go to a dos prompt and change to the folder we created for syslinux, our example was c:\syslinux. Go to a subfolder called WIN32 so we should be in DOS at c:\syslinux\win32. Run c:\syslinux\win32\syslinux.exe (thumb drive letter) (example: c:\syslinux\win32\syslinux.exe e:). This will install a MBR that points to e:\syslinux.cfg.
Reboot machine and choose thumb drive. It may throw a small syntax error up (remember- functional not pretty) but Ubuntu should boot right up. If it doesn't immediately work, you might have to use some different switches with syslinux something like syslinux.exe -sfma e:. Throws it into a more compatible, slower mode right at boot up but some older motherboards like it that way! If you want a little better boot menu, you can modify the syslinux.cfg with notepad.
This should work without damaging anything but you never know, be careful and backup data that is important before messing with the MBR stuff. Do not point at the hard drive with syslinux, you'll reboot and and it won't be pretty. Windows with a syslinux MBR would not be a happy camper.
