Re: Advice on First HTPC
The components you listed are good but as ruwacked mentioned I would start with an Intel HD integrated graphics.
Both the Core i3-5xx and Core i5-6xx series processors support the Intel HD Graphics when paired with an H55 or H57 chipset.
For a primary HTPC I disagree with ruwucked that an i5 is “way overkill”. I have an i3-540 and i5-670 (reviewed to be published in the near future) and I highly recommend both but absolutely prefer the i5 for a primary HTPC. For pure audiovideo playback either processor will suffice but if you run commercial detection software andor video conversion the i5 offers a significant improvement over the i3. It really comes down to what you want to accomplish.
I wouldn’t worry about the power supply, my i3-540 DH57JG idles at 24W and at load between 33W to 42W which is powered by a 102W picoPSU.
The i5-670 DH57DD didn’t use much more until I added added a few more drivers and peripherals
For 3D support the current Intel hardware does support 3D; Intel is working on adding 3D support to their HD Graphics lineup but we currently do know whether existing hardware will be forward compatible. I honestly would not worry about it. If needed you can always add a discrete card later when DX11 is more mainstream.