From above I would choose Logitech. Their most systems seems to have more BOOM (bass) than other (if you compare the xact setup side by side). Most people like that but its personal preference. I have logitech 640 = 400RMS 5.1 system. Quite loud, never really went more than half the volume :)
u know Faizy, with this much budget you are better off buying Yamaha wooden base 5.1 system (really kick ass) but if you could increase your budget to $1,500 (which I know you can't) then check out BOSE 2.1 in Best Buy. I have 'em and I love 'em.
I've been using the Cambridge Works surround system for about 3 yrs, don't remember the exact model. And when I'm playing any games (like Doom3) at night it scares the bejeebers out of me at times.