1. Although I haven't done it myself, it seems to be as simple as installing the drive in your computer and running a program which formats it as a ReplayTV drive. This program also has the ability to copy any shows you previously had, but that function is buggy, I guess. Then just install the drive into your Replay.

2. The favorite is DVArchive. It acts as a ReplayTV on your local network, so any shows that you've downloaded into DVArchive can be streamed back to your ReplayTV as if you actually had a second one.

3. When compard to current and past ReplayTV models: Yes, TiVo has better conflict resolution. And TiVo's searches may be more full featured. As for randomed crashes - I have heard stories. But the only way I've gotten mine to freeze is by attempting to download a show from it while it was recording another. Also, as for speed, the newest version of the ReplayTV software does appear to make menu response a bit quicker. And there are reports that replacing the drive with an 8MB cache version (Maxtor or WD) have also sped up response time.

A lot of the same information gets repeated over on the ReplayTV section of AVSForum, because newbies keep showing up and asking the same old questions. So it might be worth your while to do a little reading there, and then ask someone who knows more about the TiVo units. I chose Replay because of the networking features. At the time, TiVo required warranty voiding mods in order to get those abilities. And the most I'd consider doing to my Replay would be a drive upgrade. But DVArchive makes that unnecessary.