This is actually not that difficult, even though it may appear daunting.
You need a raspberry pi with 512MB (including power adapter and enclosure).
You need a SD card (should be class 10 and at least 4GB; although we recommend 8GB or more)
You need appropriate cables (HDMI / RCA / 35mm) and/or gender changers, depending on your intended application.
You need the .img file.
You need an image writing software tool (and computer with, or an external, SD card reader)
You need a bit of patience. B)
Raspberry Pi model B
OK, you need a Model B Raspberry Pi which comes with 512MB of RAM (there is a B+, which should work as well):
http://www.raspberrypi.org/product/model-b/
There are a number of online shops to get your Raspberry Pi. When you get it, you do not need to get the SD card if you have one available. You SHOULD get a power supply rated for your geographical location, although you can power the device plugged into a USB source (such as a computer or a capable TV or monitor or portable battery pack or ...) with a standard USB to microUSB cable. And, you should get an enclosure to keep the electronic bits out of harm's way. If you get a kit (which might be recommended), you will get the power adapter and possibly a SD card and enclosure.
NB: Power supply is a known fail point. Without enough / proper power, a Raspberry Pi may not work, or could behave eratically / strangely, without being an obvious power problem.
Raspberry Pi kits are relatively inexpensive, somewhere sub CAD$100 (ie. ~CAD$70.00)
Class 10 SD card
If you do not get a SD card with your Pi, be sure to ensure the SD card you get is a Class 10. It should be labelled on the packaging (and possibly the card itself). Class 10 cards are intended for high performance and also tend to be more resiliant (used for digital cameras). If you opt for the model B+, it takes a microSD card. These are classed the same as standard SD cards.
NB: SD cards are known fail points. While we do everything we can to make efficient and appropriate use of the cards, they can have a limited life, especially based on quality. We recommend a known, reputable brand which should provide you with stable, long lasting use of your AEBL.
Video and/or Audio cables (oh, and a network cable)
The AEBL will work merrily on its own, so long as it is powered up. Unless you connect your AEBL to an output device (TV, monitor, speakers), it just sits there and you can only just watch the pretty lights.
Out of the box, the Pi works with (standard) HDMI (both audio and video) and RCA video and 35mm audio jacks. Depending on your configuration needs, you can use HDMI for video, while using 35mm for audio. In the event that your application requires it, you may want a 35mm to RCA cable splitter / gender changer. Also, a HDMI to DVI cable gender changer also works for video (only).
About that network cable
You WILL need to connect your AEBL to the internet, in order for it to install and configure. Once it is configured, you WILL need to connect to it with the network cable (until you have wifi enabled at a later date) in order to generally interact with the AEBL in the beginning, such as for adding content to the device.
Why not wifi?
Wifi works. But when it comes to a stable, fast and reliable connection, especially for installation, cable is king. For that reason, installation should only be done by cable. If you eventually add wifi to your AEBL, just note that it is only as stable and fast as wireless can be.
On to the .img file
Unless you obtain a bootable AEBL SD card, you need to create one. For that, you need the current AEBL image which can be downloaded from dropbox:
https://www.dropbox.com/s/tf0wgewtjqqcu1l/140815-aeblpi.img
WARNING: The image is 2.7GB. This could be important to note for those with slow connections or bandwidth limits.
Did we mention it is 2.7GB? It is as small as we could make it, thankfully it's not 8GB. Even though it is small(ish) in size, once installed, it will expand to use your entire SD card. so for our own personal use, we use a 64GB SD card. :)
Otherwise... we don't talk much about the size of the image.
NB: Please be sure to keep a copy of the image, in the event that you ever need to re-install the image.
Put image there
Mac people... sorry, you are on your own. If we knew of a good tool on a Mac to write images to SD card, we would mention it here -> (this space intentionally left blank)
Seriously, if you know of a good tool (or if we eventually find out about one), we will mention it here. Oh, apparently there ARE tools:
http://elinux.org/RPi_Easy_SD_Card_Setup#Flashing_the_SD_card_using_Mac_OSX
What we WILL NOT mention, is HOW to write the image to the SD card, as that is dependent on the software you use, so read your manuals.
So, you need a computer, of course, and that computer should have an appropriate SD card reader installed, or you should get an external, USB SD card reader and plug it into your computer.
For Windows, the WinImage utility is probably the go to tool:
http://www.winimage.com/
For Linux, a tool such as ImageWriter works well for this purpose (yes, we use Ubuntu):
https://apps.ubuntu.com/cat/applications/precise/usb-imagewriter/
Now, ImageWriter is only available on Ubuntu 10.04 to 12.10, so this may not be an option for you. Check your linux distribution for possible graphical tools to burn a .img file to SD card.
Of course, you could always fall back to the trusty DD tool, but for support purposes, we prefer to recommend something that is point and click. Here's what RPi says about this:
http://elinux.org/RPi_Easy_SD_Card_Setup#Flashing_the_SD_Card_using_Linux_.28including_on_a_Pi.21.29
And Ubuntu says this about writing to SD cards (see below ImageWriter for DD instructions):
https://help.ubuntu.com/community/Installation/FromImgFiles#Ubuntu
Basically, the function is something like this:
sudo dd if=/path/to/downloaded.img of=/dev/devicenode bs=1M
Where if (input file) is the AEBL image path and name and of (output file) is the device id of the SD card you are writing to.
How ever you do it, get your image burnt to your SD card.
We DID mention something about patience, in passing.
So now that you have all your necessary hardware, and your image is on your SD card, this is the process:
DO NOT POWER UP THE DEVICE, YET!
+ Insert card into Raspberry Pi
+ Connect appropriate audio / video cables to Raspberry Pi and output devices
+ Connect ethernet cable to Raspberry Pi
+ Make sure OTHER END of ethernet cable connected to Internet available switch or router
+ NOW, you connect the Raspberry Pi to power
And...
wait...
If connected to video, you will see some text scrolling across the screen. This is normal. Disregard.
If you are properly connected to the internet with the AEBL, it will then go out and grab all the additional files it needs to install and configure itself. This process will likely entail the device rebooting itself twice.
The patience, part... this process all depends on the speed of the network. The process can take anywhere from 20 minutes to 40 minutes or more. You MUST be patient. Failure to wait long enough and unplugging the device from power or the internet can result in a corrupted image, requiring you to go back to the "write image to SD card" bit.
We should offer our appology now. We do not have a "please wait, installing and configuring device" splash screen.
So, how will you know the AEBL is installed and configured and ready for use? After the last reboot, the device will start up and begin to play through a default, token video that is about two minutes long and loops, endlessly. This is your indicator the device is ready. You can now start using it, or feel comfortable to disconnect it from power, for later use.
Congratulations on getting your AEBL device installed!