I ve used diskkeeper and found notable difference… try it for a week before tagging it good or bad… auto defrag option can be turned off , if needed…
the 2010 version comes wit intelliwrite feature which prevents fragmentation before it even occurs, by arranging files while writing files on hard drive / installing programs…
ditto… I have owned/used PerfectDisk, Diskeeper, Ulitmate Defrag, Puran, Defraggler, MyDefrag, Asuslogic… Ended up using the built in one.