After my experiences with installing VS 2005 SP1, I decided I wasn't going to get worked up over a long install for this one. So I actually started the install process before I left the office yesterday and then (gasp!) left the laptop there to go home and enjoy the evening. Came in this morning, checked the install log (it went well) rebooted and I now how an updated VS 2008 with less stress :)
On looking at the logfile it did take nearly over an hour and a half to install so I'm glad I didn't try to "do work" while it was going and now I know also to just let it install the same way when I update my VPC's later.