I've been reading alot of comments on this iMac forum about owners complaining of spinning beach balls when using their 4-5 year old iMacs. I have the same situation with my 2006 model running Tiger. So I've been wondering if OS X Macs need periodic hard drive defragging like the Classic Macs did (running systems 7, 8 and 9)? If so, what utility do you use to defrag?