First time builder looking for help

If you can, go with Intel-branded board. They are stable and have an Intel network interface. Many people often overlook this and get a board with a Realtek NIC which can end up causing headaches for many users. If you want Micro-ATX, you should consider their H67 or H61 boards. If you want to go cheap and don't need more than client functionality or hardware-based transcoding, you can get away with something like a SandyBridge-based Pentium or even Celeron.

4GB RAM is acceptable for most cases.

Save a few bucks and get the 380W version of the EarthWatts power supply. You save initially and a bit more on your monthly power bill. Even 380W is overkill for your system. More is not better with power supplies (unless you truly do need it e.g. running a monster gaming GPU).

40GB will work for the SSD, but consider 60GB because it gives a bit more flexibility. You can potentially run into issues installing service packs with smaller SSD sizes depending on what applications you install.

SDV = Switched Digital Video. It is a technology used by some cable companies to allow multiple channels to share the same bandwidth since not every channel is being watched all the time everywhere in the cable system. Using SDV, the subscriber requests that a channel be sent when tuning it. Due to the nature of CableCARD, this requires a SDV adapter which the cable provider must give to CableCARD subscribers. The SDV adapter is plugged into the CableCARD device via USB.

Hopefully, you're on a cable system that doesn't employ SDV since it requires you to just have one more thing laying around to hook up. You might be able to determine this by looking at a list we've been maintaining for various cable systems here.

That's correct regarding the quad tuner. You can record four programs simultaneously (or record three and watch a fourth live).

Get DDR3 1600.

I'd get at least a 60GB.

Yep.

I get that, but it's a $30-40 difference and the trade-off is that you'll be able to put more than just the OS on it. 32 isn't big enough, 40 is really tight, 60 is OK, I don't use anything < 90 (but I like to install apps that most people won't).

I used a 64GB vertex 2 as my htpc OS drive for a couple years, but I just replaced it with a 120GB (samsung 840 pro, but that part doesnt really matter).

I found that if you want to use a 64GB you are going to have to spend a little more effort making sure you don't install too much and are getting rid of temp files. Every so often I'd have to clear off some room because I was down to a couple GBs free.

its not a huge difference, but I don't think i'll have to bother with that now that Im at 120GB. looking at slickdeals or the deals forums at various larger messageboards (i use hardforums for this purpose) you can get a solid new 120GB for ~$90 (and there are a couple options out there at the moment). If you can swing the difference, id suggest it.

Just wait a few days and you can probably find a SSD on sale online somewhere.. shop around.