[texanpenguin]

The main reason PCs are used so much in web-design is that, unlike print design and imaging/video work, web-pages are viewed again by people with computers, most of whom have PCs.

That is, a web-designer would have to be pretty careless not to test on (and build around the flaws of) Internet Explorer on Windows, since that's where most people will see the final product.

That having been said, I know a lot of people who do their web design work on Macs and do compatibility testing on the PC browsers (instead of the other way around), myself included.