While Lord British would probably jump at such an opportunity (just look at the support he gave Exult), you would first need to convince EA to actually sign a contract with GOG. While there has been an announcement of a big publisher joining GOG in the future, we cannot know that is it EA, or if it would ever join. While I join you in calling for a GOG Ultima release, your only option right now is to either buy the collection somewhere else online or use an emulator (Exult for UVII) or play some the the remakes (U5:Lazarus and U6Project for the Dungeon Siege engine are two brilliant example of what fans can do).

You don't need Win98 my friend. Dosbox and Exult should get you most pc Ultimas. Ultima 9 definately works on XP (be sure to get the 1.19 fan patch for NOCD and improved D3D support).

For remakes and similar, I would suggest heading here:

http://www.ultimaaiera.com/

However, I've had very little issue running them in dosbox. The only one I've not tried to get working is U9, all the rest are fine.

I'm told Exult is a better option for Ultima 7 + SI, with a few tweaks here and there.

[edit] as for GOG getting them, EA are the major issue as de_Monteynard mentions above. Richard Garriott actually still has the rights to certain characters such as Lord British, so it would require both their permissions, but EA would definitely be the stumbling block. I'd happily re-buy them all though, since I only have a boxed copy of The Complete Ultima 7 at the moment.

EA needs to get their ass on GOG sharpish. They're on Steam, so it's not like they still insist on sticking to their own distribution thingy any more.

I still have to admit I enjoyed Ultima IX a lot. It's not the best game but it's still very good if you don't mind messing with "cheats" to circumvent a few game-breaking bugs (especially items floating way above the altars).

And yes, they all work fine in DOSBox although I'd recommend Exult for Ultima VII.