Why can't I sync my iPhone 4?

Here's the situation:

I had a MacBook to which my iPhone 4 was synced. However, for reasons unknown (dun dun dun) it crashed, and so I acquired another one. Now I'm unable to sync my iPhone 4 to this computer (OS X 10.6.8). Not only that, but the iPhone will not even appear in Finder, iTunes, or iPhoto.

Now you might be thinking, "Hm, maybe the cord or the port doesn't work." I thought of that too. Upon further investigation with "USB Prober.app" I found that my computer can tell that there's an iPhone connected to that USB port. So the cord itself is not the problem.

So far I have: restarted the computer, restarted the phone, updated the phone to the latest iOS, checked to make sure both the phone and the computer are authorized, and done an insane amount of searching on the internet machine. Still nothing. All I have left to try is to download a fresh copy of iTunes from Apple, unfortunately my internet runs at about 40kbps so it'll be some time before I can try it.

I await the infinite wisdom that is the internet to enlighten me…
Else rage-quit.

Open Software Update on your computer and check it for new updates. If there are any, then update your computer's software. I think the update that fixes your syncing problems is called something like "iPhone Compatibility Update". If updating your computer's software doesn't work, then I'd go to the Apple store and ask them for their help.