The RC1 build includes improvements in performance, stability, security, and application compatibility. You may not notice many visible changes from the Beta 3 release; all we did was listen to your feedback, fix bugs that you reported, and make final adjustments to our CSS support. I do want to call attention to two changes in particular.
First, IE7 RC1 setup automatically detects and uninstalls previous IE7 betas before trying to install IE7 so you don’t have to. We’ll post more detail on the install/uninstall process very soon.
Second, IE7 RC1 will automatically detect add-ons with known stability or compatibility problems so that end users can easily get a newer version or temporarily turn the add-on off. The most common cause of the “IE7 installed but won’t run” problem reports we’ve gotten was old versions of some toolbars. We’ve worked closely with toolbar vendors to make this experience better. Again, we’ll post more detail on this topic here very soon.
A release candidate is fundamentally different from a beta. With the exception of a very short list of issues we’re aware of and working on, we think the product is done. We’re looking to enthusiasts, developers, and IT Pros to tell us if this build has any critical, must-fix before we ship issues. The real world is much richer than our test environment and I appreciate the feedback that has helped us make the product better.