One of the reason why some people still won't migrate to GNU/Linux is the availability of an application which can do the same things as their previous application in Windows platform. Some popular Open Source application is now available for Windows platform as well, such as Firefox, OpenOffice.org, GIMP, Inkscape, Pidgin, and many more. However, there are a lot of Open Source application which works great just like the application in Windows platform, but they cannot be executed in Windows, since it's not been ported yet.
In June, LINA Project will release their product which enables a single executable written and compiled for Linux can be run with native look and feel on Windows, Mac OS X, and UNIX operating systems. We still don't know anything about this project (but you can download the White Paper), but it's quite promising. For now, you can look at their website or watch the video provided by them.