k3n - I too have the Janome MC 6600. Absolutely love it and what a breeze to use. Still haven't got the hang of automatic threader, but have no problem doing it the old way. Get a free class if you can. It will get you started. The gal I had, showed me al kinds of tricks and solutions. I bought the extra bobbins ( make sure you get the correct ones or it ill mess you up) and extra thread cones so I wouldn't have to make extra trips (150 miles) to sewing machine shop. The knee lift comes in very handy when quilting and turning. Oh, don't forget extra needles.
The accu feed is a dream. Now I can sew without worry on organza, silks, etc. Anyway, enjoy your new machine.