I Just purchased my PSP..... It's a PSP-1004 and had a 2.71 firmware initially.On the spot I asked the shop guy to downgrade it to 1.5 firmware,which he did. I came back home ...transfered a game iso and an emulator to my 2GB MS.When i tried to run the game i wasn't able to,It said please insert any UMD..... I havnt got no UMD with me and dont have money left to purchase one. I had heared that there is a software which runs ISOs without any UMD in drive......can someone guide. Can anyone also guide me that ...should i upgrade my PSP to some custom firmware,Where shoud i get it from,how to install it via a USB card reader cuz i dont hav the cable and any other tips which would be handy. Ive got about 17 ISOs waiting for me to play! Thanks Fellows!