When searching for a file (ie data.000) or folder name, I believe you have to go into Vista's advanced search options, and tell it to search within hidden and system folders. To browse for the folder, you also need to go into Explorer's options and tell it to show hidden and system files/folders.
If Vista remapped the savegame folder location, it should be:
C:\Users\<account name>\AppData\Local\VirtualStore\Program Files\Divine Divinity\Run\savegames
