What's the concern here? Security, performance, or user happiness?
UAC is one of the key reasons to upgrade to Vista. I certainly wouldn't recommend disabling it, and especially not in an SME context. It improves security, doesn't really hamper performance, and in a SME context should - if anything - increase user happiness. (Explanation: UAC is annoying when your running as an admin user because it keeps asking you if you really wanted to do something trivial like change your IP address. In an SME environment you - of course - will have all your users as limited users, so they're already locked down. In this context UAC is helpful, not annoying.)
Turning off Superfetch and Readyboost...why? I don't see any security issues, and depending on your exact usage and configuration, they might provide a minor performance boost. As for user happiness...I don't see them even noticing.
Aero...not a security risk, and if your machines are relatively modern not a performance issue. It could well be a serious user happiness issue, but I'd be more inclined to distribute some simple instructions for toggling it on and off, and leave it at that.