You need to see if you have an RG 6 coaxiel cable ( the cable wire ) .. if you don't you need to get one, it might help . My guess is you don't have one.
RG6 can help if the issue is a signal strength one, but that's probably not the issue here.
Regarding picture quality... analog signals will look bad on your new TV. That's regardless of whether the signals come from the cable company or a VCR. Yes, the issue is you're looking at analog signals. As you mentioned, when you watch a DTV (digital television) signal, the picture is clean. That's the advantage of digital.
Cable companies will put SOME (generally the local broadcasters) DTV signals in their basic plan. Those are the ones you scanned in. However, they need to put those signals on strange channel numbers (ie: 144-1) because the "normal" channel numbers have the analog version of the station.
If you want Food Network, ESPN, Discovery, History, etc in HD, you'll need to have your provider (Comcast in this instance) give you a box (that costs more $$ per month) that will support the HD signals. Many of those boxes also provide DVR (recording) functionality. That can also be extra $$ per month.
I HIGHLY, HIGHLY, HIGHLY suggest keeping your Samsung TV and buying a standalone DVD player. Yes, it's one more box, but if you're not going BluRay, you can get a DVD player for <$50. Heck, you can get a BluRay player for <$100. Samsung has great picture quality. Another benefit is if the DVD player dies, you can only replace that instead of the entire system.
. Just check the weight limits, and make sure the tv is not too heavy. I think it will be fine though, since those new tvs are so light. We use those shelves at school for some of our Montessori materials.
