Is heartbleed a Microsoft only problem ?
No. It has nothing to do with Windows but with a particular software that handles particular types of net security, OpenSSL. Apparently, Windows is to the good on this one because Microsoft’s version of a web server, IIS, uses different software. However, if someone is running an Apache installation with OpenSSL on a Windows-based machine, the vulnerability could still be there but it wouldn’t have anything to do with Windows itself.