I think if you're looking for something simple that model will probably work just fine. When I did my research a few months ago most people recommended Synology or QNAP, primarily for the software ecosystems. Nothing has really changed in the last few months so if you're in a hurry I suggest reviewing some of the NAS threads in the last 6 months or so for more discussion (you can probably look at my post history in this part of the forum if using the search function doesn't help you find what you're looking for).
Before spending your money, I suggest reviewing Thecus' software options and see what you think. QNAP and Synology both have software demos on their websites for you to compare and they are generally considered a tier above Thecus. Many people are lifelong Synology fans similar to fans of Apple as they say the systems 'just work' (this is NOT a dig, just a comparison). Personally, I've been super happy with my QNAP and the software is plenty easy to use.
The model I got is the QNAP TS-451,
http://www.newegg.com/Product/Produc...82E16822107169, and it does everything I need it to (which is similar to your needs). I was able to find it on sale for $350, and it is my understanding that every few months it goes on that type of sale. QNAPs are generally a little cheaper than Synology's for similar hardware.
Something to keep in mind, most units at this price point (meaning under $1000) aren't adequate for HD transcoding, but if you're serving content to an HTPC, you will hopefully not need to do much transcoding. Hope that helps!