Dell's Secure Browser is a sandboxed version of Firefox
Using technology from Computers in Motion, a company that specialized in application virtualization, KACE has managed to virtualize Firefox. Without getting into the technical details, just imagine that when you click Firefox (or 'Secure Browser'), it actually boots up another operating system, and Firefox loads inside that. The other operating system is almost invisible to the user: it's the sandbox.
Secure Browser should function just like any normal browser, but you're completely immune from malware and viruses (your password could still be keylogged though, I think?) There's also the rather snazzy option of simply hitting the 'reset' button and having your browser (and its sandbox) revert back to its original state. For the retentive types -- or the nerds -- there's a page that shows how many attacks the browser has blocked.
The other popular browser that's sandboxed is Google Chrome -- and it doesn't require a 75MB download! Still, it's rather nice to have the secure option there, if you're a Firefox user -- or even better, if you have a family member that's used to Firefox but could do with the safety net afford by Secure Browser.
Note: Secure Browser really is Firefox, with a secure wrapper. I had to uninstall my current version of Firefox to get it to work -- it's obviously designed to be installed as the default browser on new computers.