NetCentrics team was kind enough to answer me almost straight away. I thought I'll share the answer, in case anyone is wondering about this issue. Here it goes:
In your case, the GTD data is already backed up on the Exchange server.
There's no special/local database for GTD. The GTD data is embedded in the Outlook data itself - in the form of additional folder/items, per-item data is kept in user-defined fields added to processed items, configuration is kept in a post item in the 'Settings' folder that GTD adds to the data.
All you need to do is setup your new Outlook profile & point it to the old Exchange account; Outlook will sync the data to the local cache; once that is fully populated, then close Outlook & install GTD.
Important: before installing GTD on the new workstation, make sure the new Outlook profile's cache has finished populating, especially the 'Settings' folder that GTD sets up; the settings post item here is the first thing that GTD looks for & if it's not established in the local cache, GTD won't find it & will create a new one & you'll have to run a recovery function to populate this properly.