Bruce,
The best thing to do is install the browsers you want to develop for. That way you're not depending on any service, you can preview pages locally, and you begin to learn the quirks of each browser. It's always best to view things with your own eyes.
Just fyi: I have Firefox 3.5, Firefox 2, Chrome, Safari, Opera, and Webkit installed on my OS X machine, then IE8, IE7, Firefox, Chrome, and Safari on my Vista and Windows 7 machines. Yes, it's a lot of browser testing, but that's the best way to make sure things work the way you want.
Note: I didn't list IE6 anywhere.
Thanks for the quick and thoughtful reply. I, like most users I expect, only use CC HTML editor to support a few sites of my own and for a couple of tax exempt orgs. I can't justify having all the browsers that are commonly used loaded and I want to be able to quickly check the appearance of my sites without uploading the files to a working site. Can I upload to a service like browsershots.org by referencing a temp file on my computer? You might add information about such services to your help files at any rate.