Why you *must* back up your iPhone to your desktop - please read
In the last week or so, a number of people have posted on the issue of syncing an iPhone to a new computer or hard disk. Some have bought a new machine, some are recovering from a disk crash. The issue is the risk of losing content from the phone when syncing to the "new" iTunes
If you have a recent iTunes backup of your phone, this is easily addressed - you just restore from the backup.
But if you don't, the problem is pretty serious. 3rd part utilities like PhoneView (mac) or TouchCopy (Windows) can help, but they're not perfect.
My point is this: You must back up your phone to your desktop frequently enough to protect yourself from this problem.
Further: You must back up your iTunes library *and* your backups to somewhere to protect yourself against disk failure.
Whatever the rights and wrongs of tethering the iPhone to iTunes on a desktop, that is the way it is, at least for now. If you want to avoid the risk and worry of lost iPhone data, you have to respect that (you don't have to like it, naturally).
Please follow this, for your sake. If you don't, those of us who can help will try to, but there's not much we'll be able to offer.
Hope this helps