dont bother selling it on here, everyone will either try to rip you off or go "omg I can get that for liek $2"
Best tip: Sell it for $1000 maybe even more in your local trading post as something like "Awsome gaming pc" "256mb video card 1gig of ram dvd-burner 5.1 surround sound" etc. Only state the good bits and some dumbass would call you up asking more, so you tell him and tell him about how it can play all these games and such..
They'll buy it for there dumbass kid. Works every time and you can run along and build a new custom computer with that $1000 thats 4x better.
Just another newbie at the moment.