I sync my TP1 (WM6.1) with multiple computers: 2 Vista 64s, 1 Vista 32, 2 XPs. The only solution that worked for me after trying everything else was to use the mobile device center/active sync on only my main computer and use PDAsync by LapLink for all the rest. It was a lifesaver:
http://www.laplink.com/pdasync/