Don't use a 150w PSU, especially one that isn't a Cosair, Seasonic, or Antec branded PSU. Those are the best brands and are the most unlikely to fail. If they do fail they are also the most unlikely to not take other components with them.
Integrated graphics slower than the HD 2000/3000 can have trouble with 1080p playback. You could bring down your CPU to a Celeron G530 if you want to (dual core 2.4GHz Sandy Bridge CPU). For an HTPC, wou probably won't notice a difference, but the i3 is more future proofed. Your choice, but I suggest against getting an AMD CPU right now. The Itel CPUs use far less power and if this is a computer that will be used often, that matters for you. They also are faster and have faster graphics than anything AMD has except for Llano, which brings us back to the power consumption argument anyway.
Despite clutchc saying that alll opinions are valid, they are not. Trust me when I say I've seen some very stupid people trying to make very bad recommendations. Also, if you want to play content off of your computer's internal storage, you will need a large hard drive because NO SSD cheaper than hundreds, even thousands of dollars (USD) has enough capacity for many movies, especially HD movies.
If by local content you meant optical disks then it won't be such a problem, but you still need a hard drive if you want to put much of anything on this machine. BEsides, there is no good reason for an SSD in a low end HTPC because the only thing it will do for you is speed up boot time and such, nothing that matters for such a machine.
If you did anything even remotely random data intensive then I would recommend an SSD, but HTPC workloads aren't too random and a hard drive doesn't provide a bottleneck at all. Besides, if you do a lot of copying movies to and from the SSd it may wear out too quickly, especially with such a low capacity drive. Too quickly being less than two or three years, depending on the model, maybe it won't be a big deal.