mythtv is a powerful program suite you can use to build a PVR. I have used it for a while now and I have'nt found any softare that meets my requirements.
My requirements is:

• I want one place for all my data on one hardware platform
• Multimedia recordings shall not depend on a single client machine that scheduling the recordings, I want that the server handle all recordings for me.
• I wan't small silent clients accessing the server

I have an AMD64 AM2 sockel Asus Pundit that I want to use as a diskless client with mythtv frontend. I'm quite curiouse about the performans gain with 64 bit platform, I don't think mythtv has any 64 bit optimisations yet but other programs might have. I will first install the system on a small spare disk (20G) and when I'm satisfied with the configuration I will move it to the server and setup a PXE boot.

• Install ubuntu dapper
• Prepare mythtv build environment
• Build mythtv, plugins and themes
• Install other programs
• Configure mythtv