On the Mac there's a huge amount of software for sound and graphic work, and Apple has bought some really first-class software such as Final Cut Pro and Magic that now run only on the Mac.
On Linux, you're right.
Hope that helps.
D
I know people rave about UNIX's based Mac. But its expensive and tied to a proprietary brand. Whereas Linux is open source, can be installed on ANY Pentium based computer and is just as stable.