Look I joined dis site in 2012 and I'm seeing alot of threads like dis and its soo annoying lol.
1: you need CFW ether 3.55 or whatever you want.
2: go and buy CFW ps3

.
3: if you don't want to spend money on a CFW ps3 then your not doin xp lobbys lol.
4: downgrade is your last opition you need to buy E3 flasher and look for tut.
5: I wouldn't do the downgrade on your own because you need to know Wat your doin/in your case your gonna brick your ps3.
Have a nice day people <3