well it depeneds on your needs. Windows is good for software because, so much software is built for it. On the other hand linux is good for programmers(what i heard) and it is gets its secureness because it is unix based. Mac is for graphics mostly, cause it supports firewire and there is lots of good multimedia software for it. I use windows xp mostly beause i have some games and i use swift 3d.
i gotta run cya later.