I've used many different pm tools (including fastrack) on both win and mac machines. But, I must say, that fastrack 9 is the BEST pm application on the either the mac or win enviornment. it's simple to use, less expensive than most pm tools and has the features that i and my peers use. the collaboration feature has converted windows users in my office, from ms project to fastrack! not to mention, that we're able to open our current ms project files in fastrack 9 without any problems (and send it back to project users).
the only downside, is that they haven't added effort driven scheduling to their capabilities...which ms project does have.
regardless, if you need a pm tool, go with fastrack!