I've had to move my Outlook to my TabletPC Convertable Gateway m285 running Vista Ultimate RC1 and Office 2007 B2TR.
I hooked up my WM5 - nada - just a file and music Sync dialog. <read below on the hack>
Once I got the Sync working - ooooo pretty and functional brand new Windows Mobile Device Center
How to:
Looked around, took me like 15mins to find a solution to sync my WM5 to Outlook2007:
Use RegEdit to add a key called “WHOS” to HKEY_LOCAL_MACHINE/Software/Microsoft
Connect your device and go to Windows Update.
A new 7.0MB update will be available that will allow you to sync after a manual reboot.
Credit To Mike Byrns here