Lindows was always seen as the dirty cousin being neither one thing or another.
Over the last couple of years Linux has made enormous strides in what was always one of its greatest strengths but also its greatest weakness.
Installing software on Windows you get a package that contains EVERYTHING that program needs to run. Installing it puts stuff all over the hard disk, some in the windows directory some elsewhere etc. Whilst this worked to a degree it did mean that you could end up with an older program replacing a shared file with an old version which would break other things you have installed. e.g. at our local church we use Powerpoint, PowerDVD and a specialist church package called Songshow. We have a big issue in that if you try running all three at the same time if you don't start them up in a specific order they all start crashing at random intervals due to different DLLs being loaded into memory being incompatible.
Linux however doesn't do that, a piece of software only ever contains the core software. If it requires a shared library you need to install that as well. This often got us into a thing called dependancy hell as it was sometimes hard to work out what was needed by what and then they also had other dependancies. Now we have some superb package management tools.
In gentoo its called emerge, Mandrivas is urpmi. If I want to install something I just call the main package. e.g. emerge firefox This will work out what firefox needs to run, see what is already installed, get the latest versions of any other packages , download everything automatically and install it. That way you always have the latest versions of shared libraries, you can never overwrite them accidentally and you don't even have to mess about using CD's/DVDs, everything is available from the FTP servers of whatever distro you need. Literally thousands and thousands of pieces of software(99.999% FREE)
One of the things that Bill is worried about is the creep that Linux is making. Windows is used on PCs a few mobiles and pocket PCs. Thats pretty much it. Linux being free, stable, secure and extensible is being used on everything from Mainframes/PCs, servers, Phones, Micorwaves, routers, even MP3 players.Its this creep that will make linux a major player. before you know it there will be more people developing for linux than windows (actually we are already there) and their skills will bring all sorts of new exciting things to market. You like the new areo desktop in Vista? Pah, Linux did it a year or so back. thats just one example