At work, I switched from Windows to Mac about 4 months ago. So far, I’m very happy with that. The MacBook Pro I got from work is an Intel Core 2 Duo machine, the OS X interface is beautiful and virtually all software I need runs on Mac.
It sounds like a toy, doesn't it? "Puppy Linux". So cute, and when it first boots you'll hear "Woof-Woof" as a help screen opens.
I do like BSD OSEs, but I think the most interesting thing about the release of PC-BSD is that the download page incudes a VMware image.
GrandPerspective and Disk Inventory X are two free Mac OS X apps that give graphical views of where your disk space is being used.