Put your high-priority programs and files in the most easily-accessed parts of your hard drive -- the outer edge -- with UltimateDefrag, a free Windows utility. The program does all the normal data-ordering of a standard defragmenting app at about the same speed, but lets you choose what data to place where.
It's the ultimate pick-me-up for those who feel like they're losing control of their system.
Appropriately enough, the program can analyze your drive to see which files have been most recently accessed to help you in your custom defrag operation (even dictators need advisers...). UltimateDefrag can be set to run as your default defrag tool, as well as set to run only when a screensaver is active.