[Hampshire] Booting without HDD/CD

Hi all

Can anyone point me to a few links on booting a laptop to a Linux distro (Ubuntu I think) without any sort of optical drive?

I'm thinking of buying a used laptop and I've found one for £200. It's an IBM thinkpad of sorts (the vendor hasn't supplied the full details yet). Apparently it has an install of XP on a built in flash drive, but (with apparently only 256Mv RAM - I thought Windows XP Professional - nada) what I want to do is install some sort of Linux distro on it.

Am I correct in thinking this is the way to go:

1) Hook up the USB HDD to any PC with a CD drive
2) Boot PC from Ubuntu disk
3) Install Ubuntu to the USB drive making very sure not to wipe that PC's HDD.
4) Make sure it's bootable i.e. boot the PC from the USB HDD I've just installed it to.
5) Disconnect USB HDD and connect to laptop.
6) Boot laptop from USB.

Sorry if these questions are a bit basic - it's just I spent many "happy" hours with Slackware back around 1998 trying to get the darn thing to boot from its primary IDE - hence my skepticism! - and indeed I don't think I've ever booted anything from USB What I don't want is to be lumbered with a 256Mb machine that runs XP pro very slowly!

Incidentally, for those that know about M$ licensing - is it legal for them to resell like this? I've not installed XP for a while but isn't entering your name and address still part of the install process? I guess if the flash drive contains an image of a registered working install then fair enough.

Cheers
Rob