You don't want the cream of the crop, trust me. Very few of us can afford the best headphones out there.. those that can would probably rather buy a new high-end computer's worth of parts instead.
But you probably DO want something nice. The HD555 is a great all-around headphone for gamers: it probably sounds better than anything most of you have heard, it positions sounds about as well as reasonably priced headphones can, it's comfortable and circumaural (the pads surround your ears), it can be driven straight out of a sound card's line out, and it's quite reasonably priced for a hi-fi headphone. You can acquire a new pair for $100-120, and I'd say it's worth the cash.
But that IS a little out of your budget range, and there are still good choices below that. The Sennheiser HD497 is a good all-around headphone, the Sennheiser PX100 is hard to go wrong with if you want portability, the HD515 is a decent alternative to the HD555 if you want something circumaural. I'm recommending all Sennheisers mainly because you sound like you're only really planning to use them for games, and so I don't need to give you a long obnoxious lecture on the subjectivity of sound quality.
If you really want a mic integrated into the headphones (in other words, if you want a headset, not headphones), the Sennheiser PC150 and PC160 are both pretty good for what they are. I'd say that you'd be better off with a clip-on or table-mount mic, but that's just me.
Pro gamers can use whatever they want. Once you get used to the way any halfway decent headphone images, it might as well be as be the best headphone out there for games. Noise isolation is good if you have a loud computer or loud neighbors, but beyond that games just aren't very demanding. If you want to use them for music, that's something else, but I don't know if you do.
