Have you tried wired connection from computer and slingbox to router to check transfer speed and audio/video? My linksys 300 router has 2Gb/sec on wired connections and over 100 Mb/sec wireless. This is a dumb question but are your audio and video connections directly to the slingbox or is there a receiver between them ? I had audio and no video when I had the composites running from the cablebox through the receiver to the slingbox and then to the tv. I had the audio cable direct from the cable box to the slingbox. The receiver wasn't set to the cable output. When I set to cable output I had both audio and video. Don't know if that's your problem. Sounds like the router is too slow.
Hi rcod2005, have a look to this information, it may help you with this issue with the video.
The Slingbox Answers Forum Moderator Team