Bad choice of mobo/RAM. I suggest DDR2 motherboard and RAM. You're just dumping unnecessary money into something you're not going to use/see much use in. The RAM you're getting will also drop to single channel since you're going to have 3/4 slots populated, and X48 chipsets only support dual-channel DDR3.
This is a good motherboard, I can say from personal experience. I onyl had it for a few days, but it was a great mobo.
If you get it, you can still go to 16GB ram, but now you have the option of DDR2 which is much cheaper.
I can't really comment on your audio setup, as that is your own preference. Personally, Im still using stereo speakers and are mainly happy with them, although Im getting a 5.1 setup in a few days ( hooray for birthdays )
For computer cases, I reccomend reading reviews, but its also mainly your own choice. I can say that I am extremely happy with my Antec 1200. A good set of fans is essential though...
There is absolutely no reason to get a 51$ DVD/CD burner
http://www.newegg.com/Product/Product.aspx?Item=N82E16827106266
That is the one I have and I've had absolutely 0% problems with it ( it does open a bit slowly, but no slower than any other cd/dvd drive ive had)
For the monitor, if you are able to, you can buy a VESA mount and get a bigger monitor and mount it on the wall if thats an option.