I thought similar: If it used to 'run fast', but doesn't anymore, that doesn't make sense. Unless the entire pc is running slower (ie. too many apps running and not enough free ram/clock cycles).
START->Run->msconfig | click on the "Start-up" tab : will let you remove programs from start-up. Might help a little. msconfig app shows startup items on windows xp (what I'm on), if you're on a newer version, i can almost guarantee there is a similar option for you.