Honestly, I don't see why you couldn't just use panels and then toggle the visibility based on which button they press, for example:
Left side: button1,button2,button3,button4,button5 -- you can change the properties on these to make them big, like spybot S&D, add graphics, etc.
Right side: panel1, panel2, panel3, panel4, panel5 -- these panels are all the same size and same docking and stacked on top of each other, and then you can just toggle the "Visible" property on them based on which button is clicked.
This method can be a little painful to develop only because you have to keep "sending to back" on the panels in your development interface, but it will accomplish your desired functionality, and it's not really a WTF way of doing it. If you want some sample code, I could throw together a small project for you to illustrate the idea.
As a secondary option, you could purchase a control from somebody that does this type of thing. Krypton Navigator comes to mind. Check it out on http://www.componentfactory.com/. It's pretty cheap, and it works very well. I've used it in the past.
Cheers!