Here is the link to all of the DM downloads from the RIM site:
https://www.blackberry.com/Downloads...93E4F3BB068C22
I would suggest selecting version 4.7 from the dropdown menu. You will need to decide if you also want the Roxio Media Manager-it's designed to help you transfer media between your PC and your BlackBerry. I've never had an issue with it, but sme have, and it's totally optional. If not, select the verison that dosen't mention it in the title.
Also, as you are using Vista, try logging into your PC as an Administrator beofer doing this download.