Just a word to the wise - if you're doing a lot of changes to your site (for example when setting up the site) it might be best not to activate Supercache until you're finished tweaking. I was getting served old versions of pages and it was driving me nuts. You can keep it active, but will have to manually clear the Supercache cache in the control panel if you want to be served the current version on your server. Clearing your browser cache will not help.
This is a good plug-in, just be aware of this issue when actively tweaking your site.