hey man...i just did a newegg.com search for both those cards adn the x800 xt is running for ~$180 us currency NEW, while the x1800xt runs for ~$340 us currency...dont know what $160 us currency converts to to you...but its a decent sum anyways that he ripped you off of. i mean if you take the time to overclock and have everything running like that then you should know what card is in your rig. anyone who builds their own rig should be able to rattle off each part thats in it quite easily. Id take the difference off of what the price is (well once you convert the 160 anyway), and ask him for that price. if you have the money right there in his face than i doubt he'll say no.
but your other post says that you bought it so i doubt your gonna get your money back on that bro...like i said man, make sure you know what parts your getting and what you plan on doing with it...damn if he screwed you that sucks bro...but you still got a decent rig tho...and it still should be able to handle some of those games you listed.
i have oblivion on mine right now and just bought doom 3 so i know what you mean about the new games...i want fear, prey, bf2, and hl2...but i cant justify paying another 160 bucks atleast for them now that im broke lol...ill wait for prices to go down and then buy them...oblivion and doom3 should keep me busy for a while, especially seeing how i dont have that much time to play them anyways...i played the fear expansion demo and loved it tho...i only regret beating it so quickly.
well good luck bro in getting your money back. i hope it works out, or else i guess its too saving up for a new card for ya...good luck