FWIW, I hit the activation limit in WinXP, and the activation dialog had a phone number and some numbers I had to read to the person on the line. A few minutes later everything was fine.
(I'm a MS employee but I was doing this at home with my "I'm a customer" hat on)
The Windows 7 genuine advantage warnings are hostile, they accuse the user of stealing the software and as I remember the prompt was only to go ahead and pay for another new license of Windows 7.
In any case, it's not a problem for me anymore, as I now only run a pirated copy of Windows 7 in a virtual machine on my Macbook for testing on.
(I'm a MS employee but I was doing this at home with my "I'm a customer" hat on)