You connect an Ethernet cable to both PS3's, then on Both of the PS3s go to System Settings > Data Transfer Utility > Then on the 4.20 PS3, set it so it says 'Transfer Data from Other PS3 System to This System', and do Vice Versa on the 3.55 PS3, sometimes, the data transfer will time out or whatever If you don't press okay on them both quick enough, which can infact be a pain in the ass, but just keep trying. It's really simple. The Data Transfer will send most content from the 3.55 PS3 to the 4.20 PS3, such as Patches, User Accounts, Save Games, and even the Homebrew Apps, but the Homebrew Apps won't work on the 4.20 PS3. It won't transfer the 3.55 CFW either, your 4.20 PS3 will remain on 4.20, and your 3.55 PS3 will remain on 3.55. Your Modded patches etc. will then be on your 4.20 PS3 and will be fully functional. I suggest making sure you have the patches you prefer on before you transfer, because Data Transferring is annoying as hell when you have lots of stuff on it. But you can transfer as many times as you wish. Hope I could help! ENJOY