Such a shame to let that beautiful beast of a computer go. Otherwise I have no other useful information for you other than what bearbo said. Best of luck you you!
You are welcome to rejoin the regular MacRumors discussions, psalesses. (You posted a previous question here once.)
If you do you'll find that, as you read and post, you and other members will get to know each other, which is the reason for our post-count requirment.
As a Mac user, you will probably find many discussions worth your attention, and before you know it you'll be able to use the Marketplace here. If you don't need to sell your Mac right away, that's another choice for you: converse now, sell later. The disadvantage is waiting, but the advantages are that you can get a lot out useful information from the forums and that using the Marketplace here can make it easier to buy and sell because you can deal with people who are more familiar than complete strangers.
Edit: I guess I made the same point as The Don Ditty!
Good luck with the sale...I've found it very difficult to move such high end machines. People just aren't in the market to spend what you'd be asking, and those who are are buying new anyway. Your best bet is eBay or Craigslist.