I have had bad experiences with Asrock in the past, in my personal opinion, I'd pick Gigabyte, but it's a preference thing I guess.
That hard drive went out of stock on Newegg, but Amazon has it for the same price with free shipping and everything.
You should probably get the LG DVD burner that's 1$ cheaper than the one you selected, as some of it's read and write timings are faster, and it's cheaper which is always a plus.
As for the power supply, it depends what graphics card you plan on adding in the future, but the Rosewill Green Series is respectable.
I can send you a link to a review of it, if you want. It can supply the rated amperage, and can run any single GPU setup. Of course I don't know anything about their failure rates or DOA rates, what I've heard is that it contains decent quality components and can run how it's rated to run.
As for your case selection, why spend almost 70$ on the Antec Three Hundred (Including shipping?)
If I were you, I'd get the Rosewill Blackbone(That's an excellent case) instead and possible use a combo deal with the 630w version of the power supply you selected.