Thanks for everyone's feedback. I'm a one-man-band working on one computer so having the option of personally downloading all the browsers and various versions doesn't seem plausible to me. Besides, I really like the idea of easily flipping through different browsers and overlaying (onion skin?) different renderings.
Browserlabs looks good since I work in Dreamweaver. I can't find where they list the price packages. How much is it?
Another service I found that looks like it would be really good is Multi Browser Viewer. www.multibrowserviewer.com The cost is $140 a year.
One concern I have is once I see that a certain browser/version is rendering my page badly is I have no idea how to fix it!! For example, I looked at a page using browsershots.org and the page looked good in all the browsers I selected except for MSIE 7. For some reason it was dropping the 1st column down about 800px. So now I know that there's a problem, but am unsure what to change in the code to fix it AND keep things the same in the other browsers that ARE working.
How do you guys deal with these issues?