You can use a strat for any style of music. And please dont kill the name of fender by playing green day on it! I use a strat for blues, rock, jazz, hard rock (ac/dc, heavier led zeppelin, van halen). if you have the right amp, hard rock sounds just come right out. I'm assuming your using the standard 3-coil strat. If you had humbuckers this thread would be kinda pointless.
It does not sound like crap on hard rock! if you play modern "hard rock" ( anybody after the year 2000) then yes, it will most likely sound bad, but the music is bad anyway so it would'nt matter :D