HDTV with basic cable service - tricks?

First, that item looks like a cable filter. This filter is designed for people who have broadband internet and cable TV coming into their homes on the same line; simply, the filter blocks the internet-part so it doesn't cause problems with the TV-signal. The advertisement's claims could be legitimate; however, TV picture quality is affected by many other factors (quality of signal, "dirty power" from AC lines, quality of tuner/decoder, quality of cable, etc), so, I would be sure I could return this item before buying one.

Next, if you purchase an HD cable box, you will still need an HD signal coming into the box to have HD picture. Most basic cable services do not provide HD picture. The HD cable box only decodes an incoming HD signal, and does not convert the basic picture into an HD picture. With that in mind, if you plan to subscribe to an HD service, be sure the cable box you buy is compatible with your HD provider.

Finally, for using a VCR to record and play back on VHS, it is easiest to hook up a VCR between the TV and cable box, and not between the cable input and the cable box. The cable box should be connected with the incoming cable, and often it is required to properly decode the incoming signal. (Of course, fortunately, there are alternate ways to get things set up to suit your preferences).

I hope this helps!