Nice choice on the PSU. Will you be relying on integrated graphics or are you going for a dedicated GPU?
Good choice on the CPU, if you won't be putting in a GPU then the 3225 is definitely worth it over the 3220.
I personally like Windows 8, IMO once you get used to Metro although it doesn't distract from the overall experience it doesn't really add too much either. What you're getting with Windows 8 that makes it worth buying over 7 is some great speed improvements, and a more future proof platform. I'd go for it if I were you, unless you can get a really good deal on 7.