Boxee is just one of several open source media center applications. Sam recently compiled a round up of some of the most popular, and I have been using MythTV for over a year now as a TiVO/DVR alternative.
I like MythTV for several reasons. It's not a project for the faint of heart, but it's less the fault of the software than the wild array of hardware that can be conceivably used in nearly every imaginable configuration. It is quite stable, and doesn't require hefty system specs. I didn't think overly about Boxee when I first heard of it. MythTV worked for me.
One thing that MythTV can't do, of course, is stream Netflix movies. I've all too frequently, now, run into problems with Netflix disks being a little too rough to run in my MythTV box's DVD player. This isn't the fault of MythTV -- it's a hardware/media issue.
Boxee is bringing Netflix onboard. There are a few catches, and a few bits that are a little unclear, but this might lead, at the very least, to Boxee running alongside my MythTV installation.
