I wanted to share with all of you a website that I've been using for a while to practice for FAA writtens: http://exams4pilots.org
They've got test questions for almost all the FAA tests. You can generate a test out of the appropriate bank with however many questions you want to answer. Many of the images have been uploaded, but I find it's a good idea to have a test prep guide with the Computer Testing Supplement to make it more like a real test. You can also download the supplement as a PDF from the FAA's website.
Having an ASA or Gleim or other test prep guide would be a really good idea just to be able to look up the answer and the reasoning on questions you don't understand. Actually I have an ASA 2001 Instrument test prep guide that's been excellent as it has the same question numbers as this website. I recently got the Gleim 2008 guide to the same test and it doesn't have any way to correlate. So I'd suggest finding out if the current ASA guide still has the FAA numbers and using that if you wish to use this website.
This site (or it's earlier version) have so far helped me to do really well on 4 tests. I hope it helps you too!