Here's the HTIB manual download page:
The HTIB does have optical in for audio. You should definitely use that, so that you can get true 5.1 sound. The red/white RCA cables can only carry 2-channel (2.0) sound. I don't know how much this will affect the sync issue, but IMO you should make this change and re-evaluate before spending more time on the sync issue. It could be that the audio is lagging because the sat box is slow at downmixing the 5.1 to 2.0 so it can be output over the red/white cables (however, that seems very unlikely).
If you need an optical cable, don't buy an expensive one. You can probably get a decent price at Target or something, or even cheaper online:
optical cables: http://www.monoprice.com/products/su...02&cp_id=10229
Another thing to consider trying it to change the video settings in the sat box. For instance, if you have the sat configured to ONLY output 1080i, that means the sat box will be doing video processing on all content that ISN'T 1080i before sending it to the TV. And then the TV will be doing more processing to turn the 1080i into 1080p. All that processing can be slow, and could be causing the video to lag behind the audio. I know you said the audio lags behind the video, but it seems like any change that lets you affect the speed of the audio and/or video might help you get closer to the "right" amount of lag to sync them up. So I think this is worth a try. Try configuring the sat box to output the "native format" of the content you are watching (which could be 480i, 720p, or 1080i -- you might have to "enable" each of these formats individually). That way, the sat box can skip any processing and just output the native format, and the TV can convert it directly to 1080p, which might be a faster total path. Or vise-versa -- make the sat box upscale everything to 1080i (or 1080p, but I don't think the sat box can do that) before sending it to the TV. That might give the "right" amount of lag, too.
Many TVs have features that can be turned on and off that affect the lag as well. Search the internet for "audio sync" and your TV model number to see if people have been posting about such options for your specific TV.
Alternately, if you get a receiver with HDMI support, the receiver can generally fix the sync issue using a configurable delay, or an automatic sync feature.