Vistas x64
haven't had a crash (due to vista at least) for a good while, and the file tagging/naming/general maneuvering around Explorer is pretty nice. plus it looks pretty, and they're alot more lax on driver control with SP1, and apps are either available or patchable...
Not just talking, I use Ubuntu, Kubuntu, Ubuntu Studio, XP, Vista, and 98SE, and i have to say i like vista the best.