I just finished reading Rocket Surgery Made Easy by Steve Krug and recommend you read it.
It's sub-titled The Do-It-Yourself Guide to Finding and Fixing Usability Problems.
It's a great read. He writes well, has appropriate sarcasm and wit at the right places, and delivers everything you need to know about usability testing. I bet that even usability professionals will find information in there that's of use even though it's not targeted at them. He also gets extra points for quoting Douglas Adams of Hitchhiker's Guide fame: "I love deadlines, I love the whooshing noise they make as they go by."
Right at the beginning of the book he gives you a link to an online video of someone taking a usability test and him guiding them through the test. This would really suck if you didn't have internet access close to you when you were reading the book so watch the usability video as soon as you get the book and don't even wait to get to that part.
One of the cool things that I learned (and I have no idea why I didn't think this would exist) is that you can outsource your usability testing and there are sites on the web that will do it for you. This is a no-brainer if you don't have the resources to set this up yourself and it sounds like a reasonable price to pay for the information that you'll get out of it. Just point the candidate at your site (or your beta site) and let them at it.
I thought he'd listed several online usability sites but while paging back through the book I can only find www.usertesting.com.