Hi Gene
If you get the Steam download you cannot use TDW's Generic File Patcher unless you use this work around, which is a lot of messing about.
Post #161 TDW’s Generic File Patcher Steam Installation Instructions By sirrawsrsalot
The dvd is always the best option especially if you have to do a re-install at any time in the future.
The dvd custom install also allows you to select the German crew language without having to use a mod.
Peter