Could you post some more details? When you say "coax", do you mean:
- the 75-ohm coax for talking to a satellite dish or antenna
- a "composite" RCA cable (where one cable carries the whole video signal)
- a "component" RCA cable (Y, Pr, Pb - common outputs on many DVD players)

Based on your post, I'm assuming your place is pre-wired with 75-ohm cable-TV coaxial cable that eventually finds its way to your satellite dish. My advice would be to avoid long cable runs. Long analog cables are expensive and lossy, and require video amplifiers to make things work properly. Long DVI cables aren't really available yet (?). Instead, you should have your satellite converter box right next to your TV and run a direct line between them. For now, you can use component video or S-Video, and you can later on upgrade to DVI when converter boxes start supporting it (or if you want to drive your plasma from a PC).

In theory, an HD-DirecTiVo will be a drop-in replacement for your current DirecTiVo, although the HD one also supports over-the-air (OTA) signals. That means you'd have to put an OTA antenna on the roof and run another coax down to your new TiVo box. Presumably, the HD-DirecTiVo will have component outputs. It may or may not have DVI.



As to whether to buy a super-high-res vs. cheaper plasma, my advice is generally to spend less money now, since the prices on these things are falling so fast. Anything you buy today will be obsolete in two years, regardless, so you'll feel lots better tossing/selling a $3K entry-level plasma than a $15K super-duper plasma. Besides, that same $15K super plasma may well only cost $5K in two years.