plius dar cia http://www.ntfs.com/ntfs_optimization.htm

File and Directory Fragmentation
Not only MFT but also other files and directories can be fragmented when drive becomes full and you perform lots of copying and deleting actions with files. It also slows down system performance, so using standard Defragmentation Tools regularly is advisable when you perform a lot of copy/move/delete operations on the volume. Starting from Windows 2000, Disk Defragmenter is a part of Operating System and you can find it in Computer Management console.

If you do not have such tools, you can try doing it manually. Just copy files and folders to another partition, leaving original one nearly empty, and then copy them back. This solution is less effective than using standard Defragmentation Toools, however, it could greatly improve the volume performance in case if your partition was heavily fragmented. 
Note: It's not an acceptable solution if you have security/permissions setup on these files. While copying between partitions you'll loose this information.

To prevent directory fragmentation, just perform complete drive defragmentation before installing new applications or copying lots of files onto the volume.