The card i use here at renderosity (and in other popular 3D shops...) was hacked, too last week and the guys tried to do a huge number of transactions on February 20 or 21 - including saudi-arabian airline tickets and US hotels (i am in Germany...) The guy at the fraud detection department told me he doesnt know where the data was stolen and he couldn't tell me even if he would know. But i am pretty sure that they have rather good hints where the problem is or was just by comparing which customers shop in the same online shops and which customers have similar fraud transactions - and that they will then contact the online shop which seems to be the data leak...

New card, new luck :)