I am generally tired of idiots painting a black and white picture of technology. Either you use Microsoft OR you use OSS, god forbid you ever mix and match whatever tool works best. I am done playing ideological games with technology - being "Open Source"
is not a selling point unless the code base is simple enough for your average programmer to submit patches to.
Why does it appear that your world set is limited to the union of Microsoft and Open Source Software? There are alternatives to both, such as VMWare, which falls under neither category.