I'm interested in buying a new iMac for when I go to high school next year. I'm looking at either the 17-inch 2.0GHz or the 20-inch 2.16GHz. I'm not one who knows much about technology, so I was wondering if the .16 difference of GHz makes that much of a difference in the computer's performance. Also - is this the right buy for me? All I'm really going to be doing is standard computer stuff (i.e. word documents, lots of music files, burning dvd's/CD's). Thank you!