Firmware Version - PSP Slim?

I'm planning to buy a PSP slim, but, i don't want to buy games (i want to download games).
Does anyone know (in Australia), what Firmware versions PSP slim n lites come with?
Is the firmware custom or official? (Custom has Letters behind the Firmware version e.g. 4.01 M33)
Thanks for all your help in advance!
If you don't know how to check the firmware version of your PSP -

Go to :
Settings
System Settings
System Information

And if you've never updated your PSP, tell me what it says next to "System Software"
(If you Bought it in Australia)