Well i have to say the latest info is a bit of situation changer.
So i guess really for price: performance i will be better off going down the eSata route as i will be using WD Caviar Blues for my external.
Thanks for the information guys its a real help, perhaps USB 3.0 is just a bit of a marketing gimick (Depending on your use of course).
I think it would be safe to say that thread can be closed as i have my made my mind up.
Thanks again all.