Er... that'd be great, except most Linux apps are licensed under the GPL and are open-source, so there's no way to prevent someone from porting them to Windows.
Besides, isn't it a good thing to let people run originally-Linux-only software on Windows? That way they get familiar with it, and when they switch to Linux later, they'll already be familiar with the applications.
We don't want to force anyone to use Linux. Linux is all about choice! I don't think Microsoft has a future anyway. Just give it time.
IBM might be dumping Microsoft, for starters...