I use an external HD with Ubuntu+GRUB on it. This allows me to effectively "hijack" most systems. Basically it's a permanent LiveUSB - my own system wherever I go. I use it for recovery mainly when Windows systems muck up, and for portability (as I can have my system on the go, without effecting the pc I'm borrowing, much like a LiveCD).

I'm about to update to Windows 8 now [on a new, different computer]. Is there any special measure I should take to do this?

I've seen a similar post here, but the OP had both harddrives plugged in simultaneously - that's not exactly my setup.

Thank you :)

EDIT: added for clarification that this is for a totally new computer.