It really depends on what you run on your computer.
I run a few programs that I need to start a BootUp, and with the UAC enabled and at any mode some of my apps will not start at bootup.
Example; SysInternals Process Explorer, Run As Admin, to get full functionality, will not start at BootUp,
CommView to run at Boot Up will not start.
To be able to monitor and analyze the OS activities I need to see what is happening.
Once Win 7 is released, I will probably have learned enough about it to make the setting I need for my use.