I have been lurking the forums for a few months gleaning lots of knowledge - but this is my first post - so take it for what it's worth. I thought I would chime in because I set-out to build a similar budget machine with similar requirements back in late October. My line of thinking getting into the build is that I acknowledge that I am a "tweaker" that is willing to crack open the machine now and then to improve the components on an as needed basis. I wanted to build the best machine that I could for under $500 initially.
As I have been lurking this forum, I am starting to wish that I would have looked harder at the Intel Ivy Bridge route. It still amazes me that I could have built a very low budget Celeron G540 based system to start that eventually turned it into an i7 workhorse as the price of the processors drop. I ended up going AMD with the primary driver being that I wanted the extra SATA III ports that the FM2 chipset offers. If you are thinking AMD as well, I would recommend that you look at the newer Trinity FM2 chipset vs. the Llano FM1 chipset. AMD has stated that they will be releasing at least one more processor for this architecture. As a result the components would be upgrade-able in the future.
Below is a link to the rig that I built. Overall, I am very happy with the performance to this point. (Missing my online the build list is a SiliconDust HDHomeRun HDHR3. I didn't add it because you didn't have a tuner card as part of your build).http://pcpartpicker.com/p/x3cd
While my rig is only $50 more, it has 2x memory, 2x disk, and a CPU with a benchmark score of 4225 (vs 3352 for your build). More importantly, A8-5500 is a 65 W TDP processor vs 100 W in your build - which means less heat to deal with under load. If you have to keep your build under $400 (I understand budget constraints), you could swap out the 2 TB drive for the 1 TB and the 8 GB memory for 4 GB memory like you have done in your build. That would eliminate $55 from the build.
To be fair, since putting together my build, I have tweaked it a bit. I ended up removing the DVD drive and put in an Asus Blu-Ray Burner (New Egg Black Friday sale) and added an OCZ Vertex 3 120 GB SSD (TigerDirect Black Friday sale). The SSD isn't 100% necessary - but it did add a significant improvement in application speed browsing my libraries in WMC and XBMC. If you can spare the expense, the SSD was the best of the two improvements.