I'm Felix Corke, the designer from the hanselman podcast you mentioned, so here are a couple of points from a genuine creative as opposed to a developer.
It took a long time to become used to developer tools - I'd never heard of Visual Studio, C# or any type of source control when I first started doing xaml work a few years ago. They were as alien to me as maybe Illustrator or 3DsMax would be to you.
My biggest single point is that the designer can't be expected to know developer practices - please be prepared to do a great deal of hand-holding. You won't have to learn anything new whereas the designer will be launched into a whole new scary side of app development. I made a right mess of a few solutions and checkins (and still do).
Happily, I've learned to become more of an design focussed integrator than a straight creative, and maybe this is a role you need to include in your project. This is the illustration I made for our beauty and the geek - designer/developer session at Mix - if either of you is at too far at either end of the spectrum it can be difficult understand how the other works and what their role should be.
Happy to answer any specific questions!
ps you do NOT want 100Mb+ .psd files in source control ;)
