I would keep in mind that with your power supply being as low as it is you are putting unnecessary stress on your components by adding a video card to your computer. Furthermore I would also say that any dedicated card would run stronger then running in hybrid for example say you purchased a 7850 1 gigabyte it would beat out a hybrid configuration with ease. So I would make the investment in a better power supply so you can put yourself in a position that will enable you to make a play at something more valuable for you.
Ah well for a HTPC yea I would say you would be just fine. Just ensure that you are HTPC compliant with your monitor as well as everything else and yea that's fine. It's hard to say whether or not you would be okay i would think you would be just fine even with that power supply but you are pushing the limits there. You have 65 total watts for the CPU/APU. And on AMD's website they say that in dual mode you would want a 500 watt power supply. Although something to keep in mind is that watching movies uses a lot less power then games normally. However I would try and get a higher watt power supply and avoid cutting corners on it.