I just recently bought my first sewing machine. I researched and researched and researched and figured I wanted at least a few things in my machine.
A few things I looked for:
Adjustable stitch length - handy if you'll be sewing with a lot of different fabrics
Ability to lower feed dogs - in case I want to learn free motion quilting
A machine with at least a couple stretch stitches - I heart cotton jersey
A free arm - for hemming, it's a bitch enough already
Adjustable speed - so I can floor it on the straight parts and slow down around curves as needed
A full sized heavy machine - so it doesn't bounce around
A newish machine - so it wouldn't be a total pain to get parts if something happened
Then I listened to everyone's advice about getting a first machine, took my wants with me to a local sewing machine store, and checked out what used machines they had in stock. They happened to have something that fit all my wants at a price I couldn't pass up. If I can't figure something out, I can take it in and the lady will teach me how to do it. Anytime. For free. Amazon won't do that.
So that's my advice. Read about things you think you might like to do. See what features make that possible/easy. Then head to a brick and mortar store. Sit, sew, talk, ask questions, learn, and hopefully buy if you find something you're comfortable with.
PS, that Brother machine is available at Wal-Mart for the same price.