Okay, so after trying to configure everything that I could to get a true "Full Screen" picture in my EVO running Slingplayer, I have finally got it. Here is what you need to know:
-If you are using the composite connection from your cable box to your slingbox (the red/white/yellow cables) only, you will get a smaller, scaled down picture.
-If you use a component (5 individual wires, 3 for video, 2 for audio) you WILL get a full screen image in high quality.
My trouble was I had been using composite conneciton. I re-ran my cable connections as follows.
-Cable wire into cable box
-Component cables from cable box "OUT" into "IN" of Slingbox
-Another set of component cables from "OUT" of Slingbox to television component input
-Opened set-up within the Slingbox website and reconfigured the slingbox using the component as the input rather than the composite
Here is the website video showing you in detail how to connect:
Sling Media Support - Help hooking up your Slingbox
*I use a Slingbox SOLO and it gets an awesome picture whether on wifi or 3G data (I have no 4G in my area)