Why is my MBP booting slower than my older iMac?

My iMac fully boots (which means all 6 startup-apps too) in 47 secs and my MBP in 1:43.4! I’ve made a video of it here: http://www.youtube.com/watch?v=Ef6qV53DaIU. Why? The six apps that startup at launch are Growl, Spark, Stuf, CoverSutra, the iTunes Helper and Reader Notifier (which is a very small app I think). I’m really desperate for this, it’s a 2.53GHz MBP with 4GB of memory and a 512MB video card for gods sake!

I tried my Boot Camp partition, which made it boot faster (once, by 2 secs), and even did an Archive and Install yesterday, and it’s even buggier now. I tried cleaning up with CleanMyMac, reset the PRAM a billion times (actually 3) and unplugging everything except the power cord, and it’s still slow. What’s wrong with my MBP? :’(

Davey.