MacBook Pro and Activity Monitor

Hey guys, so my macbook pro is about 3 or 4 months old... Using 10.6.2

Do any of you, by any chance, happen to know what processes should be running (seen through activity monitor) when first purchased?

2) i do not see "StartUpItems" under "Library" ...

I guess I want to know what is relevant and need to run (even background processes). I had a powerbook that just flooded with random/useless stuff that just ended up piling up and slowing down the computer. The macbook currently isn't bad at all but i just don't want to let it get to same point as the powerbook did...

thanks!