Just got a Slingbox 500. Got everything hooked up and trying to do the on screen setup. My TV does not have HDMI, only component, so I have the component cables hooked up. When I plug power in to the Slingbox, I initially get a very nice picture of the upside down "U" Slingbox logo and my TV says the picture is 480p, but after 30 seconds or a minute this disappears and I just get a garbage picture (kind of staticy but not quite what you'd normally think of as static, more like the signal being messed up) at which point my TV says the input signal is 480i. This is all still through the component video cables.
I went ahead and hooked up the composite video cable just to see what it looks like, and switched the TV to the composite input, and I get a nice picture from the Slingbox but it tells me that setup can only be completed on HDMI or component. Except I have the above problem with the component video, and my TV doesn't have HDMI at all.
I know that the component cables to the TV are just fine because I have some double-female RCA connectors where I can connect the cables coming to the Component In on the Slingbox directly to the cables that connect to the Component Out, and the picture on the TV is fine from my true video source.