ok thanks if i understand :
fw 1.5 is good
only fw 2.0 can downgrade to 1.5 version
and 2.5 cannot downgradable to 1.5
2.6 fw cannot downgradable to 1.5
so if i wanna buy psp to use it same as computer (mp3,divx....)
i must buy a 1.5 or 2.0 psp fw 's version isn't it ?