Originally posted by: ness1469
http://www.gamefaqs.com/console/ps2/game/26308.html
The 30001, I believe, is the earliest model, and is very prone to "Disc Read Errors". The more recent the model, the better it will be at lasting a long time, basically.
In the newer models, they also slimmed them down a little bit by taking out some parts that they had planned for cool ideas, but never used.
Essentially, they will all play the same games, but saving a few bucks by getting an older one may cost you more to get a new one or get it repaired later on.