the pc363d (based on the old hd555/595 headphones) is an open style headset which means a fairly large soundstage. they are noted for rather weak bass output. this set comes with an integrated soundcard for virtual surround.
the game zero is a closed style headset which means a much smaller soundstage but it games noise isolating properties and a bit stronger bass output. there is no integrated soundcard for virtual surround but you can use a soundcard with them.
to be completely honest here... both are overpriced with the pc363d being very overpriced. personally i would just use a cheaper sennheiser headset or go the seperate mic+headphone route. if that is not an option then i would say that the choice depends on if you value bass/sound isolation or open/quality more.
you can get a hd598 set of headphones ($150), pair it up with a modmic ($50) and have an open design (which is ideal for gaming) and be better off than the zeros due to a larger soundstage and quality but with a bit less bass or pair it up with a soundcard to get virtual surround (if your motherboard doesnt have it already) and be better off than the pc363d with a bit more bass.
other options...
if you prefer lots of bass, you can nab the ath-m50s for $100 open box new on ebay ($110-120 bnib) which have a bassy closed design with good quality.
if you like really bass light sound, you can nab the ad700x or ad900x for $120 or $150 which have a wider soundstage than the 363d and low bass.
your choice of course.