Chosing Acer you need the speaker set.
That leaves the case /psu,drives,keyboard and mouse.
How large (Western Digital recommended) for hard drives, primary and USB back up, do you want and do you have a preference in Blu-Ray drives?
I like plain black cases but if you have your heart set on a blinged out model now's the time.
You will need a good quality 500 watt at least psu and there's an Antec case that comes with one but we can put anything else together.
I'm not just being picky, you'll be living with this for a few years and it should fit your needs and upgrade without giving you grief.