I've been using a separate microphone and headphones for the longest time now, and I'm looking to get a *decent* headset with good sound quality, and a mic attached. Oh, and it also has to have a usb cable.
Hey grocerybag, noones replied to ya yet so I figured I'd go ahead and mention the Logitech G35. It's one of the highest rated surround sound gaming headsets. It retails at $129.99, but if you look in the right places, you might be surprised what kinda deals you can get. I got mine from a Logitech overstock seller on Ebay, brand new, but no retail packaging for $75, seller name was netdirectbargains.
Anywho, I have 2 friends that picked up some refurbished G35 headsets from a reputable ebay seller for $59.99 each, free shipping. There aren't any discernable differences between the refurbished headsets and mine. I actually originally bought the G35 from BestBuy just to compare it to my "overstock" headset, and it was exactly the same, this is all legit.