Ok so they seem to be finally listening to our complaints. With the new version you can hide the toolbar, and keep it hidden even if you open more tabs or a new window. However, here's the catch. If you start IE (I have 7.0.6001.18000) with the toolbar hidden it will not give you siteadvisor results when searching google. You have to make the toolbar appear, do a couple of searches to get it working, hide it and it's non-functioning again.
Sorry if I'm being critical here, but that doesn't seem to be a very useful feature 😛
EDIT: this is true for both XP professional and Vista home premium with IE7.
EDIT2: this is also true for yahoo search results, feedback submitted to mcafee