Lynxbird7: Hello, yes, Windows 7 is supported. I should contact GOG support to update the details.
The game also works on Linux; it just hasn't been properly tested by our QA on that platform, which is why it's not listed.
When it comes to requirements, a big plus is if your PC has an SSD, since the game is large (20 square kilometers) and we dynamically load a lot of resources from the disk.
Hopefully SATA SSD will be enough and Linux may be even better ;-)
It was a precedent here that Linux support was announced but delivered some months after that made a lot of people nervous if it was real commitment.
But in general if you are planning to support Linux it would be nice to announce it on the main page as well, for someone it can be a plus for a decision (to at least add to the Wishlist and check later).