I was about to sign up to .mac (www.mac.com) on my PC but when I went to free trial, it informed me that to get the trial, I would have to sign up using a Mac. I do have a Mac but I was wondering whether anybody could help me with the script for that.

What I would like is for someone on a PC to go to my site, and be given a customised message informing them that they can only browse the site using a Mac. I don't want a redirect, just something like the .mac system, but when somebody access's it on a Mac then the site will be displayed without a problem.

If anyone can help I would appreciate it.