I have a HDTV with basic cable line

Do I need a cable box that converts the line to HD ?

I've thought for the longest time my COAX cable receiver on my TV was broke but I called radio shack to see if they had a TV tuner VCR/DVD box I could run it to then run AV to but they said my problem was I needed a digital cable box from my cable company, any ideas?

nope

I don't need that? Cuz Its coming through via plug in right now and its all fuzzy but sound is perfect.