If you have Windows Vista installed on your computer, and own a Windows Mobile device here is a quick premier to get you started. First thing that you have to learn about Windows Vista syncing with a Windows Mobile device is that ActiveSync doesn't exist any more. The second thing that you have to learn is that the Windows Mobile Device Center (WMDC) is your new best friend.
You use the WMDC to sync your computer to your Windows Mobile device. Make sure to download the latest version of the software from the Download Center (x86 and x64). After you download and install the software you will need to set up a partnership with your device.
Note: If you're an existing ActiveSync user, and are having problems getting Windows Mobile Device Center to sync with your mobile device. Delete your existing setting in ActiveSync on your device and setup a new partnership.