<<<...This isn't really true of most real-world applications, but it gives us the best-case scenario. So if it takes 3 seconds on an average 5400 rpm drive, it will take 3.5 seconds on an average 4200 rpm drive and 2.6 seconds on the 7200 rpm drive. Keep in mind this is a best case scenario, and the real application loading performance difference will be smaller. Couple the fairly small performance differences with the fact that most people with enough memory use the hard drive very little. The hard drive is used when booting up, loading programs, and loading and saving data. The rest of the time, the hard drive is idle. Some applications are very hard drive intensive... primarily those applications that deal with data hundreds of MBs or more at a time. With video and audio recording, hard drive speed can become the limiting factor in what resolution you can record without dropping frames (video) or how many tracks can be simultaneously recorded (audio).
In this scenario, it is better to err on the side of having more performance than you need because you definitely don't want to find yourself in a situation when you can't do what you want to with the computer. Since the 60GB size is still the only drive that has 7200 RPMs, if you need or want more storage, get it. The difference in performance is small, and you'll likely find yourself wanting that extra space sooner than you would care about any performance upgrade. If you're concerned about the price of the laptop, and you want to lower it a little, dropping the speed of the hard drive might be a place where you wouldn't notice much difference, but it would save you some money. At PowerNotebooks, we primarily use Toshiba hard drives, although we use the Seagate Momentus 5400.2 100 GB and the Hitachi 7200 RPM drives, and other brands can be shipped from time to time.