If you noticed, Activesync is missing in Windows Vista RC1. To download Activesync or Mobile Device Center in Windows Vista RC1 for synching with Outlook 2007:

Use RegEdit to add a key called ?WHOS? to HKEY_LOCAL_MACHINE/Software/Microsoft, connect your Windows Mobile device and go to Microsoft Windows Update. A new 7.0MB update will be available that will allow you to sync after a manual reboot.

Via Geekswithblogs