Although many feel that the Raspberry Pi is a nerdy, kids or hobbyist device that has no place in the real world, the $35 mini computer that looks like a low diet cracker is actually a nifty piece of kit that can be transformed into a quiet and powerful HTPC media player.
The Raspberry Pi comes available in two versions, the Model A and the preferred Model B that comes with ethernet, HDMI, 2 x USB ports and 512Mb of ram. The Pi can with a little bit of time and, along with the addition of a few add-ons that you probably have lying around, easily be converted into a cheap to make and run and virtually silent media streamer.
So firstly you will need to buy a Pi which you can do from a number of places, just google it to find sources. You will also need a HDMI cable, an SD card (2G upwards and class 6 or better), USB keyboard and/or mouse, WiFi adapter or ethernet cable.
Just add the almost legendary XBMC media center software to your Pi using one of the software builds available. Raspbmc is probably the easiest, then you also have OpenELEC and Xbian as well. Any of these sites let you download via Windows or Mac, a Pi-optimized version of XBMC onto an SD card.
To install Raspbmc for Windows use this install page and follow instructions. For Mac and Linux owners there is a little setting up to do first then you have xbmc installed on your SD card which can be plugged into the Pi.
Then you are ready to boot up your Pi and play HD 720p video, access online TV and stream the latest movies and shows as well as play files from your home network media collection.
The software is easy to install with no technical knowledge needed, just a USB keyboard to change some settings and let you use a remote app on your tablet or smartphone.
So there you have a cheap fully functioning media center. It may not be quite as slick as a HTPC or even android running XBMC as it will not stream certain content from the web, cannot handle the hi-res fanart and cannot always handle 1080p HD streaming easily.
But that said, the Pi makes a really good and cheap media center which will work great if you have a TV that is 32 inch or below and are happy with 720p playback.
The only downside currently with the Pi, is thefact that you cannot run netflix at this time as it requires Microsoft Silverlight, and Microsoft do not support Linux or ARM versions.