Comcast and Tivo? Or Other DVR?

[Edward]

I do not have HDTV, nor do I plan on getting it. I can't afford it at
the moment.
>From what I read about Comcast's DVR service is that its crap. The

itnerface is lousy and various other issues.
So, I was thinking about getting my own DVR, but my cable box does not
have any sort of Firewire, USB or DVI ports, just composite. So how
does that work? Can I ask comcast for a cable box with digital
interfaces? Would they charge extra? Or will they laugh and tell me to
scram? I'm thinking this is their way of locking me into their
disgusting DVR service.