This is one service that I personally will not be able to provide you, a side-by-side comparison of Linux and Windows. Why? I do not use Windows and nor do I plan on installing anything from Microsoft until they have a fully free and open source product.
Anyway, here's an interesting comparison between Linux and Windows (XP and Vista) determining which one is easier to install. If this is a benchmark on how Linux has improved its user experience, then I'd say that it is starting to be very, very competitive.
Now if only we'd get software developers to recognize our favorite platform and port their applications on it, then we can definitely say that linux desktop is definitely here.