I'm looking to build a mini-itx system and for the most part have selected all the components already. Since I plan on using a picoPSU, 150w is about as high I can possibly go. I read this article from the site: http://www.silentpcreview.com/article959-page8.html

My first impression would have been, that'll never run using only a 65w adapter. The C2D E7200 is a 65w CPU and then coupled with the other components I don't see how it could run without issues. However, they said it ran find. In my setup, I'm looking at using either an i5 or i7 (depends on budget at the time), using only 65w TDP models. Technically speaking, my system should be around the same power requirements as their test configuration.

My planned configuration:
ASRock H67M-ITX/HT motherboard
Intel i7-2600S, i5-2500S, i5-2405S (still debating)
Samsung 2x4GB DDR3 1333 (VLP)
Crucial 64GB SSD Sata3
WD Green 1TB 64mb 5400rpm Sata2

If that can actually run with only 65w, then using a 150w PSU might give me room for a small dedicated graphics card later on if I feel the HD2000/3000 doesn't cut it. But what do you guys think?

Side note: I looked at getting a Nexus Psile case (would have to ditch 1 hdd though), but the lack of available is making it difficult to consider. I'm currently rendering a model of my own design.

Intel ratings do not give a good indication of actual power consumption on their own. Looking at tables for the whole line would be give a better indication. I'm not sure you'd be able to run the parts above on a 65W PSU. It would depend on the details I guess but the slowest CPU would of course be the safest bet.
But you'd be fine with 150W or even 120W. If you want to add even a modest graphics card later, best not use an 80W...

I don't understand your choice of CPUs. You say budget is an issue but they're not the cheapest ones and I don't know what features they have in common over the cheaper options like the 2400S.
FYI, a 2310 is almost certainly not going to consume anything like 95W. And a 2300 might not actually consume significantly more than a 2600S (but don't quote me on that: I don't know really).

Budget doesn't necessarily mean cheapest. When I say budget, it's not so much do I have that much money but more like do I want to spend that much. I don't like spending money, but I don't want to build a system that's overpowered by a cell phone either. There's about a $100 difference with the i7 over the i5. Because of the 3D modelling, I'm attracted to the i7's hyper-threading which the i5's don't have. But I just read an article stating the i7 was designed for triple channel memory whereas i5 was for dual-channel. Well, the board I selected only has two ram slots and I don't know if the i7 would have lower performance on the dual channel than an i5 due to it being optimized for triple channel. The 8GB of ram is a big must for me, I'm currently hitting over 5 in use as it is and sometimes use up over 6. (current system only has 4gb installed, so it starts running a bit slow).

All 3 CPUs listed have a 65w TDP, according to Intel's website.
http://ark.intel.com/Compare.aspx?ids=52215,52211,55446,

The 2405S has the HD3000 graphics whereas the others have HD2000. If I do determine there's room for a video card, this will become irrelevant and narrow my choice to simply i5 or i7.

Also, does anyone know if onboard sound can be tied into the HDMI output with Intel HD graphics?

No one much likes Intel boards, but if you are looking for reduced power consumption they consistently outperform other brands. Seems like they make low power utilization a design priority. So if that is a priority for you... use an Intel motherboard.

Also, the fewer features it has, the less likely the motherboard will burn watts.

The TDP ratings for CPUs represent the highest wattage the chips can burn. All the Sandy Bridge CPUs idle around 4 watts. Almost all the time you use them they will be at idle or near idle.... especially a 4 core Sandy Bridge. Unless your usage includes running benchmarks or doing AV encoding, you will never get near their TDP... even if you do they will safely shut themselves down.

So the key factor driving energy usage is the Motherboard. Consider an Intel Motherboard, with energy efficient memory, a low wattage SSD and the low cost i5-2405S all run with the 150 watt PicoPSU (I think it will deliver about 110 watts of 12v... but you should double check that).

Thanks for the thoughts. I read some benchmarks on the various processors. Oddly, the 2400s(2.5ghz) outperforms the 2500s(2.7ghz). While the i7 still shows a considerable gain over the others, I think the i5-2405S will be a good choice. Newegg has it for around $215.

Far as memory goes, using two 4GB Samsung sticks. They're very low profile and are 40nm instead of 60nm, which they claim uses almost half the power of other sticks.

The 2.5" Crucial SSD (sata3) appears to be the one of the fastest on the market with excellent reviews and claims a tiny 0.15w when active. Don't think I can get any lower than that.

Its hard to say for certain which is the lowest consumption drive, all websites measure it differently, some after the PSU some before.... and even then some have certain things enable in windows others dont... but im average i would say the Samsung 470, Intel X25m and Kingston V100+ seems to consume less than Crucials, not by this im saying there is huge difference. Here is a chart of consumption between some ssd done by storage review, you can see there that Samsung idles extremly low.