I've been upgrading components this week. Switching from a series 2 Tivo to a series 3 HD Tivo is an overall win. The multi card lets you record two different shows at the same time. Plus it can record HDTV.
The Apple TV goes along with it really well. Anything on itunes can be viewed and played on your TV.
Plus, I was able to pull several components out (like my old tuner) and donate them, freeing up a lot of space.