There are quite a few, as people have said, but to add another perspective -- I'm not concerned that much about money (although a couple years/servers in and it would start to hurt) but more about lock-in.
I have to run Windows servers, use Microsoft's IDE, etc. What if Server 2012 is absolutely terrible (hey, it's happened before). What if some insanely huge security hole is discovered in IIS (again...). You're hosed. In the land of open-source you can just do a 15 minute down-time to switch to nginx (or 10+ other options), set up some new servers running a different distro, whatever.
It's just too worrying to purposefully dig yourself into a hole where you live and die by your vendor. It's not as if their products are all that great, either. I certainly wouldn't want to develop on Windows, and I'd be even less happy about forcing potential employees to do so.
TL;DR: Why do you expect to hear of many MS based start-ups? There just isn't that much compelling founders.
I have to run Windows servers, use Microsoft's IDE, etc. What if Server 2012 is absolutely terrible (hey, it's happened before). What if some insanely huge security hole is discovered in IIS (again...). You're hosed. In the land of open-source you can just do a 15 minute down-time to switch to nginx (or 10+ other options), set up some new servers running a different distro, whatever.
It's just too worrying to purposefully dig yourself into a hole where you live and die by your vendor. It's not as if their products are all that great, either. I certainly wouldn't want to develop on Windows, and I'd be even less happy about forcing potential employees to do so.
TL;DR: Why do you expect to hear of many MS based start-ups? There just isn't that much compelling founders.