I'm not sure how other operating systems work, but in Ubuntu Linux all I have to do to change the layout is to go to
System - Preferences - Keyboard - Layouts (tab) - <select layout you wish to use>
If it isn't there, you just click Add, select the language, and then select the layout. I think it would be much better if the layout was selectable this way. (you can also use an applet that switches between added layouts. This is useful if other people want to use your computer)