The J-channel is what you want around the windows. Don't forget to 'over-lap' the J-channel on the TOP of the window over that of the sides. THis way, the water runs OVER the verticle J-channel; NOT under it. The trick is a little hard to describe but I'm sure an installation book, especially the one from Ashland-Davis, will show you.
You'll have to alluminum-cap the windows. If you hang around any Roofing & Retailer shop, you'll find a contractor or 2 or 3 that may let one of their 'helpers' do your windows as a side-job. Cash only. That's what you want. BUt to be sure that you're getting a fair shake, have an installer or 2 (from the Yellow Pages) price it for you. Other than that, you'll need a Brake to do the job.