I think having two machines - one PC with Windows and associated programs, and one Mac with the OS X and associated programs would be fun.
One could learn both platforms and associated programs, and would therefore be able to benefit from both worlds (or sides of the fence).
They are both just machines (or an OS and programs on a machine) and of course, you get what you pay for in machines - whether it be a car, an appliance, a shop tool, or a computer. If you keep your tools in good shape, they can last quite some time.
"There is no accounting for taste" as they say, so to each his / her own, and celebrate the differences.
For my part, I currently run a notebook with Windows, and plan to invest (at some point) in a Mac. I do like the iMac design utilizing the monitor housing to hold the MoBo and associated hardwares. This is very nice for someone who needs or wants to conserve space.
The hard part - IMO - is the application expenses after purchasing a machine with an OS. This makes investing in any machine a significant financial burden if you run professional level office, graphic, and / or design software. It would be really nice if you would purchase a piece of software that has a Windows based disc, and a Mac based disc included and a license for installing one copy on each platform - all for the current price of one platform.