Why would the x1800 XT be outperforming the 7800 GTX in any game with any settings?
And i personally have a x1800 xl and it plays everything right now at max or close to max. I have F.E.A.R set at max and plays completely smooth. However the 7800 GT is a great card i've heard about on here and read. So i would go for whichever one is cheaper.