please do not say norton ever again. Norton utilities is byfar the worst investment possible. Instead of actually defragging your files for os x, norton actually MOVES them. Yes even the most recent version, in fact i took pictures of my test dummy macs using norton and sent them into norton. The farggin /private/etc folder ended up in /Users and junk like that .....go figure. Many other people i know have had this happen as well...and norton denies that file moving is possible.... What a bunch of liers.
Ah yes and people PANTHER IS NOT THE ONLY MAC OS WITH AUTO DEFRAG. Auto defrag is in the filesystem itself. Panther just has this enabled by default. Isn't it funny how apple enabled journalising and auto defrag in panther by default but not in the other oses...stupid company.
Here is a nifty article about disk optomization:
http://docs.info.apple.com/article.html?artnum=25668