Blitzbox doesn't work on any Gaming Platforms.
My brother ended up returning his, because it didn't work at all.
What he found to make it a LOT easier, was putting a wireless switch in the middle of a room (on a shelf etc.) and than routed the PS3s wireless internet adapter to our SOHO, for an XBOX360, you can purchase a wireless adapter to plug into the back of it. and hook up to your SOHO as my brother did. for a Wii, same deal with the XBOX 360 as my friend did.
Everything in your topography is good to go. Just needs some modifications.
Also, I can't speak for anyone elses experience, but in my experience, Belkin products don't seem to work all that good. They will do a decent job, but not very good of one.
Linksys and CISCO products seem to work incredibly well.