This is a known problem. It has to do with the way images are attached in this forum software. They're actually attachments, not coded into the page as regular JPEGs. I'm not sure what the solution is, but other Mac users should be able to help. I believe that OS9 won't work. There are different versions of OSX so you might check and see if you have the latest version.

As for Macs being the way to go for graphics, I believe that was true 5+ years ago, but I don't think it's true anymore. In fact, there's tons of photo-related software available now that's only written for PCs. The PC market is much, much bigger and economics dictate what and how much software is available. Macs are nice. But don't believe the hype.