No, those ARE
PCs. You load your OS, etc of choice on there.
Really.. they are just compressing EVERYTHING into a small package.
Seen quite a number used with Linux, then just XMBC or something on it.. very slim.
Or put windows on it, with whatever other apps, you want.
Personaly, I like the HTPC concept better that some like Roku's, etc... just for the fact, you CAN put anything on it.
My media SERVER itself, is on my server box (using PLEX).. but I have a PC for playback on my basement setup. Mind you its a full size at the moment. By default, its mostly used and running the plex PLAYER app for media playback, stored on the server.
(though one COULD store and playback on one device). But also allows me to web browse.. and anything else. I just got 2 wired 360 controller's from a friend.. and plan on putting some ARCADE emulation games on there as well.
The zotac ones, come in 2 flavors.. semi pre-configured with Hard Drive and ram already... or you can get more barebones, and add what you want.
Here.. we are not using them for HTPC.. but could more than handle it (and are actually DESIGNED for that usage). But we are running windows 7, on a 320g drive, 4g ram have a monitor (touch screen) pluged in via HDMI, and a barcode scanner. Works flawlessly.
Have both wired and wireless connections as well often.
Usually sit around the $500 price range. (depending on specs)
If you need/want any more details/spec.. just ask. I have them handy here to look at
Once my full size in the basement goes, this will likely be my next choice... just for SIZE alone. Its barely the size of 1/2 of a normal PC power supply.