To automate your weekly defrag session:
- Click Start, Programs, Accessories, System Tools, and then choose Scheduled Tasks (or if you have Task Scheduler running in your System Tray, you can just double-click that).
- Now double-click Add Scheduled Task and click Next.
- Now choose Disk Defragmenter from the list of programs, and click Next.
- Now select the frequency with which you want to run the defrag program, then click Next.
- Now choose the day and time. If you leave your computer on all the time, set the Defragmenter to operate during the night, while you're sleeping.