The basics are. Some front ends are more successful and better supported than others, so some movement has occurred in people's choices. Standard development and improvement cycle for the popular ones.
Hardware wise, the only real move has been to SSD's for OS and app drives to speed the loading process, and faster multicore processors have enabled us to do more with less, so to speak. Investments in powerful 1080p systems are half of what they were 3 years ago, unless you want the best of the best.
HDMI from the GPU for video and sound is the standard. Dual and more tv tuners (which will do HD and SD TV) as well as cablecard tuners are commonplace now and affordable without having to jump through hoops to make them work.
Popular programs (that I use) include:
People also use WHS and WMC8, as well as jriver, xbmc, and some even us WMP and Media Center as rolled out in windows without addons. SAGEtv is dead, as are a few other older apps.
As for it's primary use - my server/HTPC stores all my ripped music and movies and TV series off CD, Bluray and DVD and plays them back as I desire. I control it all via my Logitech Harmony 900, no keyboard, mouse, or other weirdness needed.
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