hm. this is turning into quite the tangled thread. maybe an admin can break it up?

I am not an authority on mythtv, just a happy user, but the first question you need to answer in setting up a box is what kind of tuner do you want to have.

there are two types, digital or analog, and I would select mine based on if I had digital or analog cable service. If you really want to have fun get too cards, myth supports that nicely, and the analog cards are pretty cheap (around 50 bucks). I run a ati tv-wonder pci card, but I had that before myth, luckily it runs smoothly, but if i had my choice I would get a hauppage card.

After that the hardware isn't too specific beyond your standard linux compatible hardware, but here are a few of the things you should keep in mind as the minimal for a happy set up.

A decent graphics card, one of the lower-cost nvidia cards should do nicely. Mine performs great on a geforce 4 fx 128 a ~90$ card.

A decent processor, if your processor is too slow you won't be able to naviagate myth easily or more importantly use all it's cool video playback features. I have a pentium 4 2.2 ghz, you should set the minimum around a 1.6 ghz processor I'd say.

Sound, as you can see from this thread, tends to be a pain in the ass if you have the wrong cards. Id look around the mythtv site if i was you and figure out who's had a lot of success with what card and get that. the sb audigy 2 I have I do not recommend.

You are going to want at least 60gb of hard drive space to keep all your recorded shows for the week. More is better if you are an archiving pack rat. I have myth converting my shows to mpeg on the fly, which is prettty easy to set up, with this a half hour show with decent looking compression takes up about 512mb of space. Without compression you are looking at around 1.1g per half hour. you do the math on that one.

for in infrared reciever there are a lot of choices, id browse around the lirc site and see what they recommend at get one of those. itll cost you ~50$