To be fair, Outlook is much better than Mail, mail is a good piece of software but the layout is just annoying and it's a bit dated. I tend to use different bits of software for different situations, plus I have a habit of buying everything on the app store, i.e. PS, Capture One, Aperture (which is soon to be redundant!), LR, then there's iWork, iLife, MSOffice 2011 etc, every program has its little perk although to be fair, I still love Office 2011. It just works, and if you have an SSD installed, you find that things just load instantly, it takes my 27'' around 7 seconds to start up from the button being pressed. One gripe with windows used to be the wait on Photoshop loading the plugins - on the iMac it's just....
Anyway, each OS has its perks, my home network still runs on a windows based server - my wife is a dentist and she uses windows because there aren't enough companies out there designing software for mac, especially for the digital xray machine etc!