Surely you jest, 5400 RPM? You must have much more patience than most people. I consider 7200 RPM a minimum, and occasionally have paid a little extra to get 10K RPM for good disk performance (e.g. WD Velociraptor).
Overall, I've been very disappointed in the performance of the "green" drives. They sacrifice too much in the name of smaller energy drain. They do have their place, say in point-of-sale or other low-demand applications. But a system I use daily for real work or play? No way. I replaced the 5400 hard drive in my portable with a 7200; made a noticeable and pleasant difference there too.
Samsung eco-greens are “fast” 5400 RPM. I have read many review where people say this. Find it more responsive than their 7200RPM
Of course all things being equal 7200rpm drives are faster but...