QUOTE(jgonzo432 @ Nov 10 2008, 12:08 PM)

Thanks for the input. This machine would basically be a HTPC.
Will it be an HTPC that's out in the open, where it can be seen, and more importantly, HEARD? If so, then stick with mATX, get a decent HTPC case, and spend some time/money/research on quiet hardware that reduces system noise- IE: good quality, quiet 120mm fans, and a case that will accomodate them, fanless video card, fanless chipset cooler on mobo, rubberized fan and drive mounts, a high quality and QUIET PSU (which that case definitely doesn't have), etc.
Cheaping out on a HTPC that's out in the open will drive you nuts and not impress anyone if it's got horrible fan noise, so believe me, it's worth the extra effort to avoid something that sounds like a 747 taking off sitting in your viewing room.
IF on the other hand, you're going to locate it in an AV cabinet, hall closet, or another room, etc. where it's out of sight and earshot of where you'll be watching it, then get whatever rig with a full ATX mobo, cheap-ass case, and don't sweat the details other than making sure everything is Mac-compatible and as powerful as you want.
By the way, your basic choice of parts is mostly fine- I'd say move up to a better video card range though, and stick with fanless.
An HTPC doesn't need the most bleeding edge comp possible. I have several older Athlon based HTPCs of FAR lesser stats than your list, that all handle HD video at 1080p just fine. (One running Plex Media Center for OSX- which rocks!) That system would certainly handle DVD, BluRay and Tivo-function with HD video.
QUOTE
I chose that board due to the fact that it allows for overclocking the processor.
Since a highly visable HTPC is always a tradeoff between performance/heat/noise- you may not want to focus on overclocking unless, once again, you're sure you can cool the PC without it sounding like a 747. Choice of case is crucial: cheap-o cases can have poor airflow and then be really loud with hot, overclocked parts stuffed inside. They generally don't make good visable HTPCs.