Well i built a system about 6 months ago and it has a 6950 2gb card it in. My monitor resolution is 1366x768. My motherboard supports PCIe Gen 3 cards so would it be better for me to go with a card like the 670 or upgrade my monitor instead?
If you want to keep your games at maximum detail, get the 670 first, then save for a screen.
If you enjoy high resolution, but dont mind having to turn your graphics settings down for some games, get the screen.