Comcast cable box scrambling UNSCRAMBLED channels?

Just got off the phone with a Comcast Cable rep and I couldn't be more frustrated. I currently subscribe to Comcast Digital Cable and a I have a 'non HD box' - its a POS Motorola Box with only composite out and no DVR. They wanted primo $$ for a DVR so I'm just waiting to get my HTPC up and running to put it to the man.

Here's what the box is doing: If I try to go to the digital channels (Fox-D, NBC-D, etc) through the cable box, I get audio and scrambled video (lots of green blurry images). However, the cable is also feeding directly to my Samsung LN46A750 and I can receive all the 'HD' channels that are clear QAM. So what I have determined, and hoping somebody else can confirm, is that the Cable Box is taking a clear QAM digital signal and scrambling it, preventing me from viewing through the cable box. I cannot recieve ANY hd channels through the box but with the tv I can reveive at least ABC, CBS, NBC, FOX, PHL17, and some others I don't really care about... Is this even LEGAL? Marketing scheme to get me to pay for a HD box?

I called customer support and told them what I was experiencing, hoping it was just an issue with the box, and she told me that if I wanted the hd channels, I would have to pay $6 more a month for a HD box - and still no DVR. I told her, "how do you expect me to pay extra for something I'm already paying for... these channels are available over the air and clear QAM over the cable signal. I'm paying for digital cable!" she, of course, was zero help.

Anybody else experience this issue? Thanks for the help.