I used Windows almost all my life. From time to time I tried Linux(mostly Ubuntu) but the lack of photoshop/drivers/flash player made me install Windows again.
Two years ago I was hired by a company who had only an iMac available. I didn't like it a lot at the beginning. Didn't know a lot about the system(i didn't know it was based on *nix either). The only programs I knew where photoshop and dreamweaver.
I still ran Windows Xp, Vista and Linux at home.
Today I only have Ubuntu at home and Mac at work. I will not go back to windows unless I have to. Vista gave me headaches and I had to upgrade my laptop to only have a nice browsing experience. Xp had it's problems too: I personally had to do a reinstall it every 6 months or so. Also who wants to run a 7 years old OS?
Today there is nothing for me on Windows. I would completely switch to Linux but I need Photoshop and Coda just helps a lot when coding.
I hate the pricing for Macs but I do consider them the best laptops out there. I prefer to pay 500$ more for a mac than to buy a D*ll or similar.
Now I'm looking to buy the new MacBook Pro and triple boot with Linux Mint/Ubuntu and Windows.
I plan to only use Linux Mint or Ubuntu and have Windows Xp installed virtually so I can use photoshop and test in IE.
Cheers