[alphaxi3]

Since WM7 sync'ing is cloud based then you should be able to sync with as many PC's as you want. I haven't sync'd with more than two PC's yet, but I do not think this is a limitation any longer. Sync'ing is done via Windows Live so you will need to create a Windows Live ID if you do not have one yet.

Zune lets you sync up to five phones per log in ID and phones can be swapped out. You sync your phone to the PC to have it added to the Zune phone list. I do not think Zune sync'ing is limited either even though you register your phone to the PC by Zune. Zune on the PC is the only place the phone is registered the phone does not register PC's so it should not care how many you use.