A couple of people have dealt with the same dilemna that you speak of an come up with similar solutions. I recall reading on the winamp forums of someone developing a skin for winamp designed with uber big buttons. Now why would he do that? Cause he was using it with his home-made, built-in touch screen. (Well the touch screen wasn't home made, but he made the mounting and covering and stuff.) It sat in the middle space behind the stick, if I recall correctly. I can't seem to find the one I read, but here is a very similar one:
http://forums.audiworld.com/a4/msgs/1734601.phtml. So anyway, if you can get a touchscreen, and you can fit your laptop/computer components (howabout a
mini-ITX computer) in the dash or somewhere up front, you should be ok. Try searching about it some more, I'm sure lots of people have put computers for media playing in their cars. The WiFi part is awesome. Drive in to your garage, pull some files from your main computer or whatever, and drive out
.