If you're going DirecTV, an HTPC setup would require going with the Hauppauge component capture board; other than that, the Gefen HD-PVR with component inputs would be your other alternative. Both of these options are going to incur some loss of quality, since they capture via component, which means reencoding the video. Dunno what the options are for these setups for IR blasters or otherwise controlling the box, or if it'd be manual; I'd suggest checking out the corresponding threads in the HDTV Recorders and HTPC forums.
However, I've heard the HR20 and HR21 are pretty decent these days - not TiVo quality, but getting somewhat close. Also, you do have eSATA storage expansion available, if that helps. I've heard the Dish DVRs are better, but DirecTV has the better selection of networks - guess it's subjective which is more important.
I'm also in Rapid City, and have a Series3 TiVo with Knology - the HD channel selection isn't as wide as with DirecTV of course, but I do love my TiVo, and HDnet Movies is lovely.