You should also mention that it's equipped with a Blu-ray Disc drive so people can watch movies in full HD (1080p).
The 60GB model is also the only one that has emotion chip allowing you to play PS1/PS2 games. The 80GB model has an emulation software which isn't as reliable as the emotion chip. It should work with most of the games though. The 40GB will not be able to play PS1 and PS2 games at all.