Welcome, Ed!
Best advice I can give you is to start with working code (SDK samples are a good place to find some of this) and keep chipping away at them until they resemble your final product.
There are a few open source Media Center projects out there as well which are useful sources of reference, and some excellent Media Center-focused development blogs.
In no particular order, these are all worth a browse, especially their archives:
http://thedigitallifestyle.com/cs/blogs/developer/default.aspx
http://www.samsaffron.com/
http://mobilewares.spaces.live.com/
http://www.olphro.de/wordpress/
http://blog.milliesoft.co.uk/
http://chaocracy.com/blogs/ogre/default.aspx
http://blogs.msdn.com/toub/default.aspx
Stephen Harding also has a beta version of his MCML development book available for free/donation download at http://push-a-button.com/products/books/index.php which is a good summary of the info you'll need to get going with.
Also be aware that while there is a ton of useful info buried in the sandbox here, the site search function is broken for content older than about two months at the moment -- so Google is a better way to track down content (possibly with a site:mediacentersandbox.com qualifier).
Enjoy!
Eddy