There wasn't any information on using GF period with I first got my 4500 man. I had to search the internet to find bits and pieces of how GF was set up.
As of the sticky and xbox, yes it's mainly for XBL and xbox consoles however if you look at how thats set up, the same thing can apply to any PC game or PC. Just substitute the XBL ports for what ever game ports you need to use for that particular game. Again, GF is for managing multiple PCs or game consoles and being all online at the same time. So if your gaming on 2 PCs and you have one or two others that are just surfing or doign email, GF just ensures that ALL gets bandwidth while your gaming PCs or consoles get most of the bandwidth depending on where you set the priority level.
If you only have on PC connected while gaming, I'd recommend using Gaming Applications feature of the 4100 and set up gaming ports there for a single PC or game console.
So in your case you are gaming on one PC and another PC is streaming and downloading and hogging some of the bandwidth. In this case, you should use GF and set up your PC for the ports you need for the game your using. Set yours at a priority 1. For the other PC thats seems to be hogging bandwidth, Set up that PC under it's own rule in GF, Local IP address> the IP address it's reserved assigned, from and to. Use Any for Protocol, Remote IP addressing 0.0.0.0 to 255.255.255.255 and Priority 200. This should give you the most bandwidth while gaming or doing anything you need to, and then while the other PC is online, making sure that it's not interfering with your connection while still giving some bandwidth it that PC.