I know Tony is talking about Windows, how about you Andy?

My iPod Touch is set up for manual management and I have accessed it from multiple iTunes databases on multiple computers for about 2 years now. When migrating from one computer to another you get all your iTunes settings moved as well.

Migrating your iTunes settings and library is also the best way to move between two computers if you're doing it all manually. Downloaded Apps live in your iTunes library in addition to your iPod/iPhone.

There are a lot of hiccups with the iTunes environment, but IMO, they're a lot easier to get around and the one we're talking about now is a once in a while thing for most people, unlike a software update which can be multiple times per year.