Here's a bit of info if you decide to upgrade your PSP and have downloaded some PS1 titles from the PlayStation Store. If you try to play them from the memory card, the first time you play them, you'll get this error:
"To use this content, you must activate the system."
Loot Ninja found some information on how exactly to do this. So if you get stuck in the position they were, here's how to get around it.