Nick, I feel you on this, I am having the exact same issue. I have talked to customer care about 10 times and exchanged a million emails with apple engineers trying to figure it out. My phone synced just fine 3 weeks ago but now it doesn't. I have re-installed windows, reinstalled itunes, restored the phone, had the phone replaced, done literally everything. Somehow I gotta think the drivers for my usb ports are messed up or there is a program interfering. I have been able to sync the phone just fine with 2 other computers with Vista and a macbook pro. I don't understand it and nobody has an answer like you said. What should we do?
here's my original post with little answers.
http://discussions.apple.com/message.jspa?messageID=5603953#5603953