Steps to buy a used PSP?

I am shopping around for a used PSP 3000 and want to make sure I don't do anything stupid.

Do I need to have the previous owner detach it from their PSN account before it will attach to my account?

If they already have games on the memory stick will I be able to keep those, or will they go away once I attach it to my account?

Anything else I should have them do to prevent myself from becoming Craigslist fodder?

If they've got any sense the previous owner will detach but if they don't then you can do it and set your own up. If they let you have a duo with any downloaded games on then once you have setup your own PSN account you won't be able to play them - so don't let them charge you extra for that!!

Thank you. That is what I was concerned about. There are at least three situations I am running into as I shop:

PSP Go with games on it - the games are useless to me.

PSP 3000Rachet and Clank - Echocrome is useless to me

PSP 3000 Rock Band- All d'loaded songs

Bummer. But knowledge is power, so I won't pay for anything I don't get to keep.