Ok... I suppose that I should be able to figure this out based on other posts, but I guess I want to know, in simple yes or no, if there is any difference between the GOG version, and the one I have on my discs (other than them being DRM free on GOG)?

I suppose the bottom line here is this: If I already have the game discs and manuals, should I bother buying this release?

Well... They did put a link to GOG in the game's main menu. First time I've seen them do that with any of their games for that matter, and I own half the catalog.

well, they made it run flawlessly on Win7 for most people - I think thats enough. Why should they change anything on the gameplay?
I'm not 100% sure, but I think in the retail version the link in the menu pointed to the sierra website, which propably doesn't exist anymore.

I didn't play it before gog got it, but I think that some people had a problem installing in onto their computers, which has been fixed.

it does not run flawlessly, anyone with up to date nvidia hardware/drivers are going to have problems in some parts of the game that make it impossible to continue. so far the only "flawless" way on win7 for me is to run it in a xp vm.

that's way I wrote "most people" not "all people". Some problems aren't found during testing.
btw I have the latest Nvidia driver installed and it runs smooth so far.

The problem is the now infamous issue that windows 7 64 bit has with 16 bit programs. Although most Windows programs done for Win95 and beyond are 32 bit, they use a 16 bit nstaller. Frustration thing is a lot of these games play perfect on Windows 7 once you get past the installation problem.