I'm upgrading from an nVidia GeForce GT220 to a GTX460 (Both 1GB), the new card arrived yesterday; and it's freakn' HUGE!
I haven't installed it yet, as I need a new power supply (also on it's way)
The games that will really set a benchmark will be Left 4 Dead 2, Grand Theft Auto IV, Battlefield: Bad Company 2 and EVE Online. However from what I can tell, my limiting factor will now be my processor.
EDIT: Okay, I bought the Power Supply Unit from PC World (a shop within the UK) on Friday. I ordered the Graphics Card from EVGA Europe on Saturday.
The Graphics card arrived yesterday, and Just Now, I got an email from PC World stating that the couriers picked my order up this morning.... UGH.
It had better be delivered today (but I know it won't be)