A little over two weeks ago I ordered a new computer. What I was after was a linux-based box that could run MythTV reliably but quietly (since it will be in the living room).
Read about the experience here
The only problem, other than breaking a PSU, is that the PCI DVB-T tuner cards that I have will not fit inside the Isis case. Ive ordered a Nova-T 500 dual tuner card to compensate (along side the replacement PSU and another 500 GB drive). The beauty of MythTV is that it will allow me to use all of the cards in separate machines, combined into one set of recordings that can be watched through any of the MythTV front-ends in the house. So thats 4 tuners allowing 4 shows to be recorded simultaneously. Eventually this may be expanded to include satellite tuners because we have a very weak digital signal around here. More on the specifics of MythTV and how its being set up in our house soon.