We did the Dtv bundle with verizon. It was hell for 4 or 5 months. I just got rid of DSL and directv and went to comcast for high speed internet phone and cable. The Cable is just an afterthought. I have built a kick butt Home Theater PC.
AMD 3.0Ghz processor
On board HD.
24TB of HDD space
ASUS BLU-RAY drive
Adding a Ceton 4 tuner Cable capture card soon.
I also have an Xbox 360 that I use as a media extender from my HTPC. In the bedroom I also have a Roku Streaming box as well.
The Roku is a great little device. As is the Boxee Box. http://www.boxee.tv/
Really all you need is a decent computer with plenty of storage space and win vista or 7.
You can make a linux media box but it is a lot more work.