I've got a Crucial M4 128 GB as my main HDD. I have a spare Caviar Black 640GB HDD which I'm thinking of using as a games disk (will partition for other things too). My steam folder is about 140 GB and my WoW folder is 31 GB. Will I notice a speed difference over using the Caviar against my current 1TB Samsung HDD or would I be better off just updating to a 256 GB Crucial M4 and flogging the 128 GB one?