The HG20 records all video and images to an internal 60GB hard drive or a SD flash drive. To get the video into the computer I just copy the desired videos from the camera's hard drive to my computer. In PD I just import the video files or folder from the Edit screen. I don't import every subfolder.
Why do you want a Popcorn Hour? Last year I build my own media center PC. It was built on an AMD HD4200 GPU and a 2.9 GHz AMD Dual core CPU. It has a 500 GB HD, Blueray/DVD drive, HDMI video/audio, SPDIF, an a HD TV tuner. In my opinion a full computer offers more flexibility than a dedicated media device.
Q9300 2.5 GHz
4 GB Ram
Nvidia 9800 GT