Stargazer made a statement. To answer your question, though, the Steam version is not compatible with the non-Steam DVD version; to get updates the game would have to be activated on Steam. The GOG patches may work with the non-Steam DVD version, but would probably require a little registry editing to create the keys the patch would look for to get the path and version information. It may be possible to extract the GOG patch contents and manually update the non-Steam DVD version, as well. GOG does not list all the patches, though, generally removing the older links when updating the full installer, so you may need to contact GOG support to get the links to the patches since the game version on the non-Steam DVD.