At first glance you may think that an AMD APU is an attempt by AMD to farm out its chip production to India, but it's actually something else. AMD decided that a CPU with an integrated Radeon-class DX11 GPU should be called an Accelerated Processing Unit or APU. It's not a lot different from motherboards with integrated graphics aside from the additional flexibility you get by being able to choose an APU to suit your needs. Since most motherboards feature Intel's horrendous integrated graphics, AMD's APUs are a welcome change.http://www.amd.com/US/PRODUCTS/DESKTOP/APU...mainstream.aspx
I recently put together a system using the AMD A6-3650, whose integrated GPU is equivalent to a Radeon HD6500 series graphics card. I selected a Biostar A55MH motherboard which features a solid UEFI bios (very fast bootup) and 8GB of Kingston DDR3-1333 memory (the board supports two sticks up to DDR3-1866).
Gaming performance is not bad (far better than anything you can achieve with an Intel GPU), but the main focus on and HTPC tends to be video playback and this is certainly an ideal system for playing back all of today's HD formats smoothly. Windows 7 performance rating for my particular APU's graphics was 6.2 - very respectable for integrated graphics (compared that to Intel's garbage GPUs which usually score below 4).
The A4 through A8 series have a TDP of 65W or greater; if you're trying to keep power usage to a minimum, the E series feature a TDP of 18W with 6300 series integrated GPUs. I think it's worth noting that the power draw of these APUs is going to depend on the system load, so the difference in power savings is probably going to be a lot less than the gap in performance between the E series and the A8 APUs...but it's always nice to have options isn't it?
APU based systems are very easy to assemble since you only need to add memory and a hard disk to get a system up and running. There are Micro ATX and Mini ITX boards available using the FM1 socket required by the APUs, allowing you to create a high-performing HTPC with low power requirements and minimal noise. If you're building and HTPC today, definitely consider using an APU from AMD.