You can have more than one computer set up to sync, but only if they are using the same music library, and you have to copy over all the itunes files in order for it to work. I’ve done this before, but i had to share my music folder, map it on the second computer (over the network) and then copy the itunes library, and app data>apple computer folder. It worked, but was a PITA because if i left w/ my laptop i had no music…
So, i went for the alternitive, Have one computer set up to sync with it, and on my laptop, if i want to update it, i have to do it manually. Not as easy as plugging it in, but easier than the other way.