Windows XP comes with a utility called Disk Defragmenter that’s an essential tool for tuning your hard disk. Disk Defragmenter’s job is to rid your hard disk of file fragmentation, which occurs when a file is stored in multiple places on a partition. Defragmenting files stores them contiguously, which greatly improves hard-disk performance because Windows XP can load each file from a single location on the disk.
Before using Disk Defragmenter, you should perform a couple of housekeeping chores:
Delete any files from your hard disk that you don’t need, as described in the previous section. Defragmenting junk files only slows down the whole process.
Check for file-system errors by running Check Disk as described in ...