I think that you have two issues to deal with. Since you are using CS2, the versions of ACR released after the release of CS3 will not work with it. I believe you need version 3.7. This link will let you download older versions of ACR:
http://www.adobe.com/support/downloa...atform=Windows
The second issue is will it work with Vista. I think that if you get the latest CS2 version that it will work OK based on my fading memory of upgrading to Vista before I upgraded to CS3. Since you said that you had a new computer, I'm assuming that you had an old computer with CS2 working on it. If so, you can copy the ACR file from the following location on the old computer to the same location on the new computer:
C:/Program Files/Common Files/Adobe/Plug-Ins/CS2/File Formats
The file should be Camera Raw.8bi.
Good luck,