I started to use Macs as my old company bought a bunch in the late '80s. The PC world was then on MS-DOS (ah remember the command interface...)

I bought my first desktop Mac in 1992 when I left that company to start my own business. That one, an LC2 was in continuous use by me until 1997 and by my daughter to 2002 - so it lasted 10 years. The new iMac I got this year is only my 4th desktop (including the LC2) since 1992. So the desktop machines are extremely reliable, and the lifetime cost is pretty good. The laptops, which I use for client sessions (training etc) will break - I've had a few with screens going. Maybe I shouldn't drop them... So get a desktop unless you really need a laptop.

Softwarewise, I have found OSX in its various guises to be very stable. I also recommend getting OSX 'the Missing Manual' book which is very comprehensive. It has a good section on setting up a Windows partition for running Parallels/VM.

What don't I like? MS Office can be a problem - I work with big files for training purposes and often crash Word and Powerpoint. In theory, you can make pdfs of your MS Office files to send to clients/co-workers, but sometimes the files become huge. I'm just at the point of investigating the various Mac iWork packages as I suspect they will make better (smaller) pdfs.

Other niggles? My oldish HP network printer stopped working when I went from 10.3/4 to OS 10.5 (leopard). It took a long time to sort that, and I'm resisting going to 10.6 (Snow Leopard) as a result. And the latest desktops come with a keyboard without a separate numeric keypad.

Apart from that, Macs have worked for me over the years.