Well... some of what rocking4christ says is true. There's not much point in using command prompt for start up items and running services, as you can do that from msconfig without command line knowledge (and even then, if you don't know what you're doing, don't touch the more user-friendly msconfig).
Defragging provides negligible improvements, despite popular belief - but then, it's also subjective to how fragmented your drive is. Also, it doesn't matter whether your hard drive is IDE, SATA, USB, or SCSI - you can still defrag it. What you want to avoid is defragging a SSD (solid state drive).