I'd go with an HD 4870. Amazing cards for the price.
http://www.newegg.com/Product/Produc...82E16814102801
And I hear they're dropping in price considerably by April, so that's another thing to look out for.
Edit - Here's a really nice combo deal with the 4870 and an i7 920, since you're probably going that route with the $1000 budget.
http://www.newegg.com/Product/ComboD...t=Combo.165214
http://www.newegg.com/Product/Produc...82E16814102801
And I hear they're dropping in price considerably by April, so that's another thing to look out for.
Edit - Here's a really nice combo deal with the 4870 and an i7 920, since you're probably going that route with the $1000 budget.
http://www.newegg.com/Product/ComboD...t=Combo.165214