Hello everyone, I am about to upgrade my MBP's hard drive and ram. I was thinking about picking the Seagate Momentus 7200.4 500GB, but is the speed noticeable compared to the 7200.4 320GB? 320GB are enough for the work I do, so I am most concerned about the speed. The 320GB is 50 cheaper so I could save up for the RAM which costs 60. Let me know what you think.