[iBook] iBook compressed files?

[Mike Urseth]

A friend has a clamshell iBook running 9.2 and was having very slow 
performance and problems with PPP.

He was advised to back up his 10 gig internal disk and reinstall 9.2, 
so he bought an external 80 gig USB disk. It took forever to transfer 
the data and when it was finished the new drive showed nearly 40 gigs!

Once he reinstalled 9.2 and his applications, the performance of the 
iBook was great and he was happy. The nagging question is how did 40 
gig fit into the 10 gig drive. I suspect that the previous owner had 
installed some sort of compression utility.

What say you?