I'm looking to buy an external HDD for use with my 722. From reading the threads so far it looks like the Western Digital My Book Essential is a good choice, regardless of storage capacity. But what I haven't found in any post is anything about 5400 RPM vs. 7200 RPM. I've been looking at a lot of drives tonight but I think I can buy either in the 750 GB version, while I don't think I can buy anything but 5400 RPM in the 500 GB version (I'm still not 100% decided on what size to go with). I understand why faster is better in theory, i.e. better overall access times, but if it doesn't matter then it just doesn't matter. In other words, if I won't notice a difference, I don't care and would just assume buy the cheaper 5400 RPM version which probably uses less electricity and should in theory last a little longer. I'd love it if WD My Book Essential users would chime in with the RPM on their drives. If you hate yours for any reason, I'd be interested in that too. Thanks in advance.