Solaris is native to SPARC processors, although I'm sure there must be some sort of x86 distributions somewhere. I personally use windows, as I do most of my unix work on lab machines, when I do wanna use unix at home, I use an emulator, the name of which completely eludes me right now.
As for microsoft, I know quite a few unis are part of MSDNAA, which gets you free microsoft software. However, this service is *******s, they'll only provide you with a one time download / product key, which means whenever you have to reinstall windows (frequently in my case), you have to contact support to get a new product key, of all the times I've contacted support, I have NEVER had any sort of response from them. My attempts to obtain windows x64 fell at the first hurdle due to the service being ****e. Ideally, I would use lnux, but i'm just plain lazy.