We normally steer clear of commodity PC parts (except video cards, because, well, those make everyone happy), but I've had an Antec Sonata case for the better part of a year and am a big fan. It's quiet, it's nice looking without being fruity, and it wasn't expensive as these things go. Now Antec has the second generation 'Sonata II' out, with a even quieter design (they ditched those punched holes in the side) and a better power supply. If you're looking for a top-shelf case that might help your PC from sounding like a whirlwind, check it out (just don't plug in the eye-searing front LEDs).
Son of Sonata: Antec Sonata II [ExtremeTech]