You need to download ALL the updates that pertain to your particular machine.
Updates for items that you obviously do not have, like Airport/Airport Express/Bluetooth are not essential to you and you can tell Software Update to ignore those types of update. Everything else needs to be downloaded and installed.
What OS are you running?
Are you one of the few who does not have a CD burner?
How often do we really have to download these updates ?
I don't need to enhance the performance of my system for burning multimedia data. Or do I ? Thanks for guiding me.