i played s4 gold with a friend a couple of months ago, we both were on windows 7 machines, i dont think that the os will be a problem. the multiplayer has some snyching issues though.
besides that, the game is much like settlers 3, just better in every part. if you like S3 you will much likely love part 4.

Thanks! I can't give a 'right answer' to an opinion thread but +1 because I always like it when the answer is one that I WANT to hear. :D I'm just finishing the Amazons of S3 and while I have gone insane with frustration a few times, I can't honestly remember having this much fun with a game since I was a kid playing Aztec on my Apple\\.

GOG will probably get it soon, they have a habit of releasing sequels months apart. Works fine apart from IIRC some people get a "black box" bug where one of the dialogue boxes is black and you can't see certain stats. Number 4 is very much like an improved version of 3. The campaigns against the dark tribe were great. I'll have to dig out my discs so I can help you :P