I disagree with rom's blanket approach - disabling all but is a good way of writing off your system ... gently gently - 1 at a time ... and check what they are before you do anything - disable your virus scanner and you are in trouble
I tend to use this
http://www.mlin.net/StartupCPL.shtml
rather than msconfig - nothing is permanent untill you decide it's ok
free space - ms recommend a minimum of 25% ... but 20 is fine.
ccleaner - stick with the basic defaults ... clean the rubbish - don't get into registry "optimisation"