Going to build a new HTPC for ony 1080p movies and family photo's

I am going to build a new HTPC for my family room and hook it up to our new 42" 1080p Phillips LCD which as 3 comp. and 3 HDMI.
I am considering using a mATX AMD780G w/ HDMI onboard with a 45w AMD X2, 2GB DDR2-800 Mem. and a notebook 2.5" 160GB harddrive w/ XP Pro 32bit or Vista HP 32bit.
the idea is to have a silent HTPC that will play 1080p movies such as Blue-Ray, HD-DVD and downloaded HD movies without lag, show back family photo's and be very energy efficient as well. Thats why I want to go with the notebook HDD and the 45W X2. I have a DVR through Dish Network, so I dont need the pc to act as a PVR/DVR. I will have a system on the network that will be my backdoor for all my media storage w/ 1.5TB storage for media.

Im pretty sure I can meet my needs with the system I have spec'ed out, but I would like some opinions on the HW and SW side of the build.

thanks

thanks, thats also why I will go with just a SATA notebook HDD too. but I need it to play all 1080p movie formats including downloaded from the web. I was considering vista, but i love the performance of xp. and the system will have to be on standby but able to back and operational my tapping a key in only seconds. (thats the only reason vista is in the mix. it has better powersavings without hanging too bad.

thank you!!! any issues with playback of 1080p movies??

With the price of RAM, you might as well get 4GB and 64-bit Vista.

I don't have a Blu-Ray player, but 1080i content plays fine.

2.3GHz should be enough, but if it was me I'd get this one:

AMD Athlon 64 X2 5050e Brisbane 2.6GHz 2 x 512KB L2 Cache Socket AM2 45W Dual-Core Processor - Retail
http://www.newegg.com/Product/Prod [...] 6819103298 $62.99

would it be better to wire the pc used for storage and the HTPC to the router than use wirelessG?

My last rig had an 2.25ghz X2 (well, Opteron 165) and even using CoreAVC as the codec for 1080p .mkv's it would still stutter occasionally, though not bad.

Will the 780g's chipset hardware decode the .mkv's?

From what I've read, the 780G can handle all 1080p reguardless of file format, even with a single core. Some mobos utilze sideband memory for some dedicated onboard graphics memory.

however, a low end graphics card will give a slightly better picture. I'm guesing it isn't anything that can be seen easily. it is also more power draw.
I think the 4550 is under 25 watts, a 4670 is 60 watts peak. so its not to much power.

I also vote for Vista64 and 4 gigs.

I've had VERY bad luck with 780G Gigabyte boards. 1 month of use out of 3 boards.