320GB is/was the biggest ever made in 2.5".

So he should have written "320 GB (pretty much the max for PATA drives that fits a Powerbook).

@Jim
"laggy and deathly slow", remember that this was current at a time when most people were still running WinXP, 10.5 must have felt like sweet heaven in comparison.
There is also that rumor that Apple didn't optimize the PPC part of Leopard in order to make users switch to intel faster, something that most likely is also the reason why the Leopard-servicepack (aka SnowLeopard) never made it to PPC.

Both Win and OSX got far less laggy today thanks to SSDs and HW several times faster than those 1.42GHz G4s, so you'd have a hard time convincing normal people that getting rid of an unnoticeable lag (in everyday light use) would be a good reason to go for a non-lagging platform that will struggle at lot of basic things.