I guarantee you this is the easiest and safest 3.40 oe-A installation guide on the net . 3.40 oe –A is a custom firmware by dark alex that is basically like a 1.5 psp with 3.40 compatibility . You can run psp iso’s , cso’s (upto 3.40 compatibility) , psx games , homebrews , and even devhook etc. This installation requires flashing so use at your own risk 3.40 oe – A installation For installing this you need a 1.5 psp or a psp with older version of custom firmware from 2.71 SE-A to 3.30 OE-A . 1) Format your psp and connect it to your PC . Make sure your battery is 100% full 2) Download the 3.40 oe-A easy installation (compiled by me) from http://igizmore.blogspot.com/2007/06/340-oe-custom-firmware-installation.html 3) Open it with WinRAR if you don’t have WinRar download it from http://www.rarlab.com/download.htm 4) So open with Winrar and copy the PSP folder to the root of your memory stick , If it asks you whether it can over write click on “YES” 5) Disconnect the psp from the PC , scroll to the game menu > memory stick and start the OE UpdateMaker 6) Some white text will come up , it will take about 3 minutes if you are using memory stick duo pro and it will return to the XMB home . Reconnect your psp to the PC. 7) There will now be a new file in PSP/GAME/OEUPDATEMAKER, named "DATA.DXAR". If it has the size of zero bytes, then format the psp and redo it . 8) Go to PSP/GAME/OEUPDATEMAKER, and move the newly created DATA.DXAR into: X:\PSP\GAME\340oeflasher . Then disconnect the psp from the PC . 9) Here comes the flashing part MAKE SURE THERE IS NO UMD IN YOUR PSP REMOVE IT IF THERE IS . 10) Make sure your battery is at least 75% (100% recommended) a. scroll to the Game menu > memory stick and start the application named 3.40 OE Firmware install. 11) It will display some pink text, press X, and it will start flashing your psp. When it finishes, you will be prompted to manually restart your PSP. And your done you now have a 3.40 0e custom firmware . It has replaced your 1.5 / older custom firmware so you can FORMAT the psp or delete the files .