Looking over your choices now...ok. I haven't played around with HTPC software, so I have no good opinions on anything specific and will just stick to hardware for now.
Heatsink - Good choice, nice and low-profile. Also quiet.
Graphics - Superfluous. The motherboard already has built-in graphics sufficient for your needs. Save the $95.
Case - Your choice based on looks and function.
Memory - 4096MB should be enough for anybody, right? But...see my next item.
MLB - Right now I'd actually prefer the
MSI 890GXM-G65. The only reason I can see for going with anything else would be for more PCI slots (such as the BIOSTAR TA890GXE) or to reuse older components (any board using DDR2) such as if you have to have a floppy drive (the MSI does not). The MSI board uses DDR3, which runs cooler than DDR2. It is the most future-resistant Micro-ATX board I see right now. And yes, getting that SB850 (as well as USB3) really
is worth it.
OS - I would upgrade to Win7 Pro instead of Home Premium. The kickers are better XP compatibility and the ability to log into your HTPC remotely using remote access. This means managing it from another computer on the network rather than dragging a keyboard and mouse over to it every time you want to do something with it.
ODD - Your choice, they're pretty much a commodity these days.
PSU - The aforementioned Silverstone Nightjar. Plenty of power with zero noise unless you want to add a screaming graphics card to the unit (which you shouldn't need what with the built-in graphics).
Storage OS - I'd replace that drive with something like the
RiDATA 32GB SLC SSD for the reasons I give above. Yes, it's a bit spendier, yes it's smaller (capacity). But it can take the abuse and hold everything you need, even with looooong uptime. Actually, if you can't afford to put in
any sort of SSD right now, just put in the drive of your choice to get you by until the price of SSDs falls, then put in something in the 32-64GB SLC range once they drop.
CPU - I would actually recommend the Phenom II X4 910e (not the ordinary 910, but the 910e). It's about $30 or so more, but it uses significantly less power (you'll earn back your $30 over the first year in power savings alone) and generates a lot less heat/uses less power (also handy for silent PSU and cramped quarters).
Recommendations only. Even if you don't end up with the components I suggest, at least consider the reasoning behind why each was chosen.
--Patrick