the grado SR60's/80's are great headphones for the casual listener who wants something better than that stock earbud sound. they can easily be driven by a soundcard's line output as well.
My setup is a little more extreme than some of you out there, but I think it was money well spent. First off, let me start by saying that the PC is a notoriously difficult environment to work with in terms of noise and interference. I opted to bypass the computer as much as I could so I use a HeadRoom MicroDAC via USB. I use kernel streaming to send out audio signals that have been unmodified by kmixer to the MicroDAC which turns the digital signals into analog. The MicroDAC is a very high quality yet affordable (and small!) DAC that bests and competes with $1000 DAC's. From the MicroDAC the signal goes straight to my Headamp Gilmore Lite amplifier (which is another high quality, affordable, and small amp). And finally from there the signal gets pumped straight into my Sennheiser HD600's w/ ugpraded Cardas cable.
I know some may think this is way too extreme, but I don't plan on upgrading this sound system for a VERY long time.