Re: How to Boot to USB (Linux or Windows)
As long as your computer supports booting to USB and the option is set in the BIOS you should be able to boot to a USB drive. You'll need to make sure the external drive has a bootloader installed on it and that it's set to boot before the internal hard drive.
When I was installing Gentoo on my laptop, I first set up an install on my external hard drive so I could work out any bugs before moving it over to my internal drive. After I was able to rsync it between the two drives. You should be able to get GRUB to work, but there are other bootloaders that you could use (such as syslinux). I don't remember all of the details of how I configured grub.conf, but if you need help I could get my external drive out and see if the config file helps me remember everything.
I'm also booting Knoppix from a USB flash drive. For that I'm using syslinux (although I'm considering switching to GRUB).
Basically, any distribution should work as long as your BIOS and bootloader are configured correctly.
Has it been a few days since I replied to your thread? Don't panic! I'm usually very busy and may forget a post if I'm extra busy (or it might just take me a while to be able to do a decent reply). If you still need help and are awaiting my reply after a few days, PM me about it.
When posting what errors you get, please give the full message. It makes helping you much easier.