I have a MacBook Pro (but I boycott McDonalds

). I use NX2, and Photoshop Elements if I need to tweak anything that cannot be done in NXView. I have used iPhoto but wanted a little more control and features. I have also installed Darktable, which is open source. It lets you upload your raw photos, and tweak them. I installed it because I also use Ubuntu Linux on a different laptop.
If you are looking for open source software for your Mac, take a look at Darktable and Gimp. Both are available for Mac. I have both of them on my Ubuntu Linux laptop. Haven't played much with the Mac version of Darktable but have used it a lot on Ubuntu. It's not hard to learn and works very well. Oh, and it's free!
When I went digital a little over 3 years ago, I first tried to use Windows and did not like the results and also felt it was just clunky, and not right somehow. About 8 months later, I bought a MacBook Pro and have never looked back. I also ended up getting rid of Windows completely (except at work) a year ago when I got a new Dell XPS 17" laptop. Installed Ubuntu Linux. I do most of my photo editing work with the Mac and everything else with Linux.
Hope that helps.
Also, I do have Microsoft Office 11 (minus Outlook), Works, and Libre Office (it's open source), among a bunch of other applications. I happen to like Libre Office and use it on all my computers, including my work PC.