Install
Windows Mobile Device Center (WMDC) to your Vista computer
Install Outlook 2007 on the Vista computer (WMDC only syncs to Outlook)
Set up a partnership between the Pocket PC and the computer
On first sync, WMDC should recognize that there is data already on the pocket pc and ask you how you wish to proceed with 3 choices: 1) Combine the data on both devices; 2) replace the data on the pocket pc with data from the computer; 3) do nothing.
You will probably want to choose the "Combine" option, but if you already have Outlook data on your computer you may wind up with some duplicate data.
Be sure you backup your pocket pc before you do this just in case something happens and you lose the data on the pocket pc.