I have "Selective Start Up" running - it's essential. About once a month, I run msconfig and "untick" the stuff that's added itself back in the meantime. The machine runs a lot faster after that treatment.
The worst offender is Quicktime QTTask.exe which adds itself in with alarming regularity. If there's one already there but unticked, it adds another and ticks it. I think it's something to do with Apple or Itunes or some such, but I've never knowingly run it.
Then there's Canon Easy-Print Toolbox (I think I've got that one sorted now).
Plus RealSched which I think is an updater for Real Time Player which I don't use but haven't removed yet.
I managed to get rid of the three Symantec Update Checkers, but it took time and Registry editing.
There are 12 items right now in my "Don't you dare!" unticked list (counting the QTTask.exe examples as one).