03-30-2012, 08:03 PM
Logic only needs the computer to run and make music however it is highly recommended that you buy a USB midi controller (which I see is on your list to buy) otherwise you will be limited to creating music solely with loops. They typically require a USB to Mini USB cable that plugs directly into your computer's usb port, not a midi cable (however if you have the right equipment interface, you can still use a standard MIDI patch cable). Logic does have a feature where you can push caps lock and it will turn your computer keyboard into a makeshift midi controller but it is rudimentary at best.
You do not need a USB audio interface if you plan to make music using loops and midi recordings, however if you plan to record stuff through a microphone, you will need one. USB audio interfaces also take some of the workload off your computer's processor by decoding and converting all the system audio for it.
Here is a basic Logic setup:
(When recording with MIDI/Synths)
MIDI keyboard controller -> computer (Logic) -> USB Audio interface -> headphones/speakers
(When recording with a microphone)
Microphone -> USB audio interface -> Computer (Logic) -> USB audio interface -> headphones/speakers
If you plan to not record with a mic or just don't have the budget for an audio interface right now
MIDI controller -> computer (logic) -> headphones/speakers via the computer's headphone jack
You can also use your computer's mic input but it will not sound nearly as good and you will probably need to invest in an adaptor. Audio interfaces use balanced inputs that are not susceptible to interference and they have on board pre amps which will allow higher volume levels. I would recommend getting one.
As far as your computer specs, they all look ok. I would recommend upping the RAM at some point (Logic is a huge memory hog) to at least 8 gigs. You can do this at microcenter for about 35 bucks.
Maye get an external hard drive at some point too.
Hope this helped!