Hello,
I installed Windows 7 Beta on my gaming machine to test it out. So far I have found it to be pretty cool. Well... better than Vista anyway which I only used for about a month before going back to XP.
One problem I am having now which I did not have with Windows XP is this. When ever I click on a structure to build it, it seems to be auto placing it. I used to be able to pick a structure (Hangar's for example) and place them where I would think they would do the most good. Now they seem to get placed in clumps around wherever a builder happens to be.
I don't remember that problem before installing Windows 7 Beta. I'm not sure why Windows 7 would cause this, but thought I would report it. I did not get any hits when I searched for Windows 7.
At any rate, I would expect this to be low on the stack of things to look at. One because I have not read every single post in the forums and this may be some sort of known issue. Two because Windows 7 is a Beta (I expected wierd behaviour). Three because Entrenchment is a Beta. With all of that, I'm amazed the thing works at all. 
FWIW: I have not seen any other problems with Sins on Windows 7.