Its supposed to, but you will not see a difference. The ONLY difference for 2.0 is the voltage. The important thing is to get a faster GPU with good stream processing and good cooling. Even if the connection was 3.0 and you had an 8800GT it would look exactly the same as 1.0 or 2.0.
gota say i also love my xfx gtx 275. though i am in 2 mind as whether to overclock it some more as reports suggest you can get a 10% increase in performance. bt im gona oc my cpu 1st see if that brings any improvements