well obviously a gx2 would be better, but also the new Dx10 cards are coming out this fall-end of this year. So i would suggest the x1900xt or even the x1800xt for that fact. Save your pennies for the DX10 cards, it WILL be worth it.(I already am )
The HIS with IceQ3 is a great model, but also make sure you have enough room for it as well, it is a space hog card. Sapphire and Ati cards are supposed to work well too. If you have the x1900xt now, dont ebay it, the highest you'll probably get is the price of a x1800xt, maybe less. Anyways, glad to help, as always
yea the Kandalf is a full tower case, and it looks like you will have plenty of room to fit all of your nice goodies. I suggest a nice amount of fans though to keep it all cool. I would go with the dell monitor actually, a lot of people on these forums claim to have the dell 20' and larger monitors and seem to have great results from them. I have a samsung syncmaster 204b 20.1' LCD and most of the dell monitors like the 20' are based from this. It gets 5ms and was a little more than the $349 monitor from dell. Anyways good luck with your new computer.