Whats better for college students, IWork or MS Office for mac?

Hey guys, I'm a junior in college and i just swapped to a mac over summer (RMBP 15") <3 it! Currently I'm running vmware fusion with my old MS office from my last computer (DELL). It's wicked glitchy and fuzzy on my RMBP, so it's about time i upgraded.

What's better and why? IWork '09 or MS Office for Mac '11

I'm a business major so I will be using Excel/Word/Powerpoint (or the mac alternatives) all the time.

Thanks for your thoughts!