Right, I followed the guide to the letter, and it worked perfectly until I went to replace lockdownd, it copied to my phone, but my O2 PAYG SIM still didn't work, and when I turned my phone off and turned it back on again, it's on the "Slide For Emergency" screen.
I don't have to go through it all again do I?
na, just open up iTunes (and make you are connected to the internet). then wait for it to activate again. that's all I had to do.