Right now I'm at about 1300 GB. I have one 1 TB drive and one 300GB drive. 300GB is just about completely full and the 1 TB isn't even close.
But another 1 TB drive would be nice. You can never have too much storage. I remember back in the days when I payed over 200 bucks for a 20mb hard drive. I don't mind slapping down 150 to 175 now for 1 TB.