POST YOUR LIST: Top Five Tasks to Keep a PC Running at Optimal Performance

Time to throw down the gauntlet for all the IT pros who pride themselves in being able to set up the most rock solid PCs in the world (before users get a hold of them, of course *WINK* *WINK*). What are the top five tasks that you would recommend for maintaining optimal performance on a PC? This can include loading software programs, tweaks to the default settings, login scripting funtions, or anything else that you can think of to help make a PC as trouble-free as possible over a long period of time.