Defrag?

[Christopher Hack]

After years of cube-envy as a pc user, I bought my own cube six months ago.
Of course, its perfect and I love it, etc.  in recent days however, it is
appearing "sluggish", taking noticeably longer to do routine operations.
with a PC, I would probably defrag the hard drive. Do maccistes do such
things, and how. I found the disk utility, and all I could find to do was
verify the permissions. I have Norton for OSX, but have read lots of
warnings on this list to avoid it.
Briefly therefore, is there any sort of routine maintenance I need to do
such as defragging? And if so how? Many thanks.

Chris