I sprung for a new MacBook Pro when they were refreshed a few months ago. The one thing that still catches me (and bugs the heck out of me) is that you can't do CMD+key shortcuts like you can in windows, such as Win+E, Win+F, Win+M. The fact that I was just getting used to Windows 7's Superbar shortcuts (Win+1, Win+2, etc.) only aggravates that more.
Thankfully there are third-party programs to bring some Windows functionality to OS X, such as MagicPrefs, Growl, and QuickSilver. And Address Book and Calendar play nicely with Exchange 2007 servers, albeit without categories.
iPhone 4! ☠☠☠ Mid-2010 15" MacBook Pro! ☠☠☠ Gateway LT2102h! ☠☠☠ Dell XPS M1210!