I will be ordering comcast digital cable as I will be moving soon. I'm signing up for their DVR and HDTV service, however I do not currently have an HDTV. I plan to get one in a month or two. If I order HDTV now and they give me their HD DVR, will I be able to connected it to my current SDTV or does their receiver only output ATSC. I asked comcast and they told me I would be able to connect a SDTV and it has a coax output, but I thought I might try to confirm with one as you as the customer service rep seemed confused.

Yes you can use a Comcast HD-DVR on a non HD tv. I use a Time Warner 3250HD on my Panasonic 13" SD TV/VCR combo. That box can output HD and you can watch HD channels with it but with bars. You can also use composite or S-Video for an SDTV.

Enrico, I'll corroborate what HDTVfan said.  My only HD set was in the shop for two weeks, and in the meantime I connected the Motorola DCH3416 from Comcast to an SD television.  The coax, S-video, and composite outputs worked perfectly well with it.  To use the component output, I had to set the DCH3416 to send it at 480i, but then it worked as well.