The 5805 is likely a good starting point, but it may be more simplified to just create one from scratch.
As far as 16 x 9 goes...it is in 16 x 9 but doesn't stretch to the edges. It's a fixed resolution...likely 480i. I've commented about this to tech and would like to see the ability to stretch and/or resize the image to fit the screen entirely.
If Roku Labs can do it on their $300 High Def Photo Bridge, Control 4 can do it on their $1,500 unit. Granted it may not be that simple, but it sure would be nice. BTW-the Roku's GUI quality is just excellent. The product itself needs work still, but the 720P GUI has razor sharp resolution on my Pioneer plasma. It allows you to select the desired output - 480i, 480p, 720p, 1080i, etc. and then allows you to custom trim the edges to make it fit perfectly out to the last pixel. This feature really needs to be looked at from Roku. That's the one thing they've mastered.