I don't think it can be done via a registry hack but I might be wrong. I tried to disable the Backup messages when I was creating a unattended install disk and failed.
I tried that solution from Thomas too, but it does not work.
I noticed that each system has different registry data under those CheckSettings value, so the data is probably machine specific (crypted?) and cannot be modified with a single setting.
Of course this is good so that no unwanted program could turn off these checks with a simple registry change, but this is not good for system administrators ...
I'm still searching but I haven't found any solution yet ...
Quote from this link Disabling a specific Action Center message via script or registry key
posted by marsmimar.
I found this true except it's not machine specific it's install specific. I was using the same machine to test installs and this reg hack would not work. The default value was different on each install and so was the value after I manually unticked it.