No. It syncs all of your data to all of your devices in mid air. lol
It also comes with an email address, contacts and a few other things.
The devices it syncs is this list:
iPod Touch
iPhone
Mac
Windows (I think only vista does it but i don't know!)
And maybe a few other devices!
Nah, XP works too. You have to install the MobileMe control panel via apple software update to get it to work on windows (afaik). But it works pretty good. I use it to keep my work and home computers synced up, as well as my ipod. I probably don't use it as much as I could, but it's been pretty handy so far.