Hi, and welcome!

Fish Tycoon for Mac has always supported windowed mode play. Simply to go the Menu screen, click on Options, and set Fullscreen mode to Off.

We would be happy to help you with getting the games on your various computers, but that's something that can't be handled on the forums. The best thing to do is to go to our support page (I've even provided the link for the appropriate question for you), and explain your request. Carla will be happy to assist you with getting the games for both platforms, as well as getting a gift copy of Fish Tycoon.