I will sometimes, when I know I actually need to (though, thats not necessarily only when its absolutely required)
Eg, some Windows Updates, driver updates, etc. Also, when I am not doing anything important. FireFox just saves my data for me, and, well, if I am not chatting, no sense bothering with that, same for email.
As for new devices, if I am using a computer under Windows XP, out of habit, I never restart (thats any plug and play devices)