Yes I have built one. I used a hauppage HD DVR and it seems to work pretty well. The picture isn't perfect, but it looks good overall. the blu-ray looks great, and so does my entire DVD collection, which I backed up in MP4 format. I have an HD3200, which is really all you need for your GPU. You don't need a whole lot of processing power, but more helps. get a big, fast hard drive, a good amount of RAM, and be sure to splurge of the tuner card. Hauppage is generally said to have the best picture, but now AMD has one, and I hear it is great.
BTW, mine is the first in my sig.