Here's where I am with the whole thing. Yesterday I bought a Razer Carcharias headset. I like them, but after some digging I'm thinking I could have done a whole lot better.
What I'm learning from these great forums is that the consensus is to buy a good set of cans and use an add on mic. Pairing said headphones with a good sound card (preferably one with a dedicated headphone amp) is essential. Also, I see a lot of talk about Dolby Headphone being a key piece of software.
After reading all of these things I've devised a plan of attack and would like some feedback on it. Sennheiser seems to get a lot of love around here and I've been eyeballing the Sennheiser 558 HD cans. I like the open design (something else I learned about from these forums) and they are highly regarded on Amazon. These would be paired with an Asus Xonar XD (which i already own) sound card, while it doesn't have the dedicated headphone amp it does have Dolby Headphone.
A little about what I'm looking for. I'm mainly interested in this setup for gaming and some music listening. Good 5.1 or 7.1 performance is important to me, not for competitive edge, but for sheer awesomeness. I'm by no means an audiophile, but I do love some good rich sound coming out of a good set of headphones. These things said, will my proposed setup meet my criteria? I'm open to suggestions in terms of comparably priced headphones (~$150) and other equipment you might view as useful or essential. Thanks for your help.