Rhys said:
Linux has a lonnnnng way to go before it replaces Windows for 99% of the population.
Linux will never replace Windows for 99% of the population...
If you look at the way Linux is designed from the kernel to the command line interface you will see how much more powerful it is than Windows and even though its designed more as a server OS, with someone willing to put the time into learning how things work it can be a perfect desktop OS with a full suite of multimedia/internet/office applications which are all easy to use.
This is why you have to type in commands to run stuff, it is not designed to be a simple point click execute, giving users the option to compile programs from source allows a high level of customization to be used, however having said that Ubuntu is one of the most n00b friendly distros and does make things a lot easier for you, and you don't infact have to type commands to install stuff, you can use a GUI tools such as Synaptic, where you just search and click install. Most of the complex command line tools have simplified GUIs to them these days, its just a case of putting the time in to find them.
To many people come to Linux expecting it to look and operate just like Windows, but the reality is that you aren't paying £300 for a retail license or whatever and everything is built by open source community of developers, a lot of it unpaid free time work.