Hi all. Just thought I'd ask all of you about this build. Understand that I am just going to be using the PC for Media Center pics and music and streaming Netflix, you tube, etc. I will have a discreet Blu Ray player for Dvd's.
I will be running Win7 64 bit. Will be lighting up a Samsung 7000 series LED 55". Also using a Pioneer VSX-919AH-K . Mobo is GIGABYTE GA-P55M-UD2 LGA 1156 Intel P55 Micro ATX.
I am confused about two things. Do I need a high-end graphics card to light up the TV and provide enough resolution? Also, will I need to add a sound card or can I run the sound off my Mobo into the receiver?
It depends on the sound quality that you find satisfactory, and the number of speakers you have in your home theater. The board you picked out will be able to send a signal through optical-spdif to your receiver that can be translated into either Dolby Digital or DTS 5.1. For 95% of people that works well. If you want 7-channel sound, you'll need a higher-end part. If you don't have 7 speakers there is little reason to spend a lot of extra money on equipment that decodes audio for channels that are never sent to a speaker. Not only does the price of the computer go up, but so does the a/v receiver.
When putting together an HTPC, sound abatement plays a bigger role than in your common computer build. High-end boards like you've picked usually don't have any trouble with fan control, but if you want to make sure, download the motherboard manual and check to see whether it has 4-pin fan connectors and that the BIOS mentions fan control. Similarly, the case fan and power supply fan can be loud. Read what people have said about their experiences with their equipment; you may need to either replace a fan or choose quiet components. The HDD (hard disk drive) is also something that you will want to pay attention to if the HTPC is within line-of-sight while you watch movies. If so, get a green drive -- they are quieter (the exception to this is if you plan on using RAID, because green drives perform poorly in RAID). If interested, a good place to find information on quiet components is at silentpcreview.com.
Make sure your BIOS supports advanced features such as wake-on-usb. This will make controlling your HTPC via a remote easier. Don't forget the remote. Most remotes are infrared (line-of-sight). I believe the windows media center remotes come with an IR receiver.
Be aware that a common mistake is building a high-end system just to find out that it is more powerful then they need and louder than a jet taking off at O'Hare. Keep that in mind when choosing parts. Bigger is not always better. For example, if you choose carefully, there are even some integrated graphics chipsets that are powerful enough to do High-Def video: amd 785g, nvidia 9300, nvidia 9400, nvidia ION (nvidia also has better hdmi audio than amd). If you want a discrete video card, expect to pay $70 or more for one that is capable of doing High-Def (the HDMI port is a good indicator).
Flash is a special animal. Both Hulu and Youtube use it. It is currently processed by the cpu (not the gpu), so you will need a beefy cpu if you need to watch flash full-screen today without any stuttering. Adobe will be releasing a fix for this sometime in the first half of this year which will allow flash to be processed by the gpu. When that fix is released, then a beefy cpu will no longer be required (unless you plan on doing heavy video transcoding or a bunch of dvd ripping).
I would wager that most audiophiles buy sound cards, but most people use the sound from the sound chip on their motherboard. The board you have chosen has a good audio chip. Sound is easy to upgrade later if you think you need to; you just need to remember to save a slot for it on your motherboard.
If you were to go Linux, you would probably want an Nvidia card since they are supported better. Windows is much easier to set up, however.