Looking very nice. I can't wait to see it completed. I know your 98 was sweet (and it's the inspiration for my 98 A4 install), and this looks like it'll be even better.
Where are you going to put the headunit? The Xenarc looks like it'll go right where the double-DIN oem headunit is now.
When you get a chance, please post pics of your headunit location, the computer parts, and the front of the screen.