based on benchmarks from everest ultimate edition, the built in windows defrag works better than 3rd party defraggers.
the good thing is that the tune up utilities defragger is basically a copy of the windows defrag, does the same thing.
i like using it because it allows me to set it to defrag all 5 hard drives when needed
when i benchmark i do the linear read test and the random read test
i used to use perfect disk (recommended on the grc security now podcast but i found that disk read performance was a little lower with it compared to the built in windows defrag.
tune up utilities basically used the windows defrag so what i do is i install tune up utilities then i disable all of its services and then i sue the defrag as a on demand tool and since on Friday i only have 1 class, i set it to defrag my 5 drives before i leave for class
even though the fragmentation never really goes about 1-2% since the way i store files is
only installed programs on drive c, then all music and installers for my favorite programs goes on drive D then all movies and videos/ anime goes on drive G
and all files used for my photo editing and 3d modeling goes on drive H
this keeps everything organized and fragmentation is rare but i is still good to do it. even 1% is too much for me

especially on drive c
soon i will be getting a new 7200 rpm 20GB hard drive where i will keep the windows page file on (i will also transfer my backup windows xp partition (great to have, just use partition magic to copy your drive c to a hidden partition. then if anything ever happens to your windows install instead of spending hours reinstalling and setting everything back up, just use partition magic to copy that backup partition over which ever xp instal that you have that messed up and in like around 10 minutes, your back up and running with no problem, (it is a big help to me since i have 3 windows xp and 1 vista install ( 1 xp install for running the microsoft visual studio (needs it's own xp install since it doesn't like creative, (installing it will cause the eax console for my audigy 2 zs to crash constantly with a ntdll.dll error )
another xp install for testing things out that may be unsafe, an a main one for gaming and other stuff