I used to use Macs years ago, and use an iBook for surfing around the house (yeah, I know... not my fauly my partner collects macs).
But I am aware that almost all Mac designers I know say Windows is a better environment to build web pages in. Purely designing, it may be that Mac's are better; but if you are building pages too...
Not only that but Windows machines are prevalent, so if you don't have an easy way to test pages in Windows, then...