WELCOME TO SPCR!
Any plans for gaming? And what kind of audio demands do you look for regarding Bluray playback?
Anandtech just had a comparison of the integrated chipsets when it comes to HTPC demands, Intel on Nvidia seems the best for right now. Although an AMD on ATI combo is good if your audio demands aren't as important.
So maybe a consideration there for you. 400-500W will be more than enough (and honestly it's hard to find quality conventional psu's rated lower than that nowadays).
You could go with a dual core, although again I'm not sure of your expected demands for the system, and I would go with 2x2GB rather than 2x1GB in the memory department.
Any of the recommended lower power psu's would be fine here: Corsair, Nexus, Seasonic. Modular is nice if you can spare the money for it.
Just for info purposes, my AMD setup with a 45W X2, 4670, HD, fans etc peaks at about 160W from the wall at full bore with Furmark and Orthos running. Just something to remember when you see some of the crazy recommendations on other forums