[erbbysam]

you could probably shut off Norton or Defender because they both do essentially the same thing but you should have the rest, you don't need Ad-Aware, Spybot & the defrag program to start up though, that may be caused by other things.
Spybot has a built in startup program tool under in it's "advanced mode" which you can use to keep non-essential things from starting up when you login (ie. itunes ect.)