C++ or XML gauges?

I just browsed through the FSX SDK and it says XML gauges are preferred but that C++ can be used to make gauges if more flexibility is needed. It didn't say that kind of flexibility.

So my question is this and I think I know the answer already. For someone trying to create some state of the art gauges for a glass cockpit aircraft (from scratch) with a lot of bells and whistles...is C++ the best language to use?

If so, I'm planning on purchasing Visual Studio 2005 since it has the latest C++.Net and I'll use that to design gauges.

Thanks for any confirmation from gauge developers.
I would say, use both ! :)
In my opinion, the cabin_comfort sample of the SP1 SDK is a perfect design example involving both languages: XML for displaying information and C/C++ for expanding aircraft logic.
Keep the graphics part exclusively in XML (excepted for seldom cases, like GPS), since it's very easy to do (using the ace.exe built-in editor). For anything more complex than an altimeter, put all calculations in a C++ module (to avoid hassle of writing bloated RPN expression). This design pattern ensures both flexibility and reusability of your components.