Here are some Frequently Asked Questions.
Which PSP model should I get?
That depends on your budget and what you want from your console. Take a look the home page for links to the overview of each model.
What kind of memory card does the PSP use?
The PSP 1000, 2000 & 3000 use Memory Stick PRO Duo. However you can get an micro SD to PRO Duo adapter, so you can use a micro SD card, which has larger capacity and is cheaper than the PRO Duo memory sticks.
What kind of memory card does the PSP Go use?
The PSP Go use a Memory Stick Micro (M2) The is no M2 to micro SD adapter, so you need to use an original Memory Stick Micro with the PSP Go. There is however an M2 Dummy Adapter in the form of a flat cable which connects to an SD card.