I forked out about $350 bucks for a low end ACER PC. There were many considerations here. I wasn't too concerned about computational horsepower as I figured the box would be used mostly for slide shows, watching video, and web browsing.
Noise was a concern. It's a nice coincidence that slow PC's generate less heat, have smaller power supplies, and correspondingly tiny, quiet, fans. I went to several local stores just to put my ear on the cases of potential models (only drew a few odd looks).
This pick comes with 512MB RAM, DVD burner, plenty of USB 2.0 ports, on-board audio/video. I removed the modem card that was included. I also got rid of the mouse and keyboard, but more on that in a minute.