I have had the same problem, an error that my computer could not be activated, 0X8007232B is the error I received. And for me clicking on Activate now or change product key did nothing. I am using Vista Business and I think that the problem is caused by the default way that Vista tries to activate itself for volume license accounts. It looks for the server that will allow it to validate based on the KMS method. Since we are just evaluating Vista (< 25 copies), we don't have one of those so validation method errors out.
I tried the SLUI 4 at a command prompt and got a Activate by Phone dialog box that only allowed me to select Afghanistan. That didn't help.
The solution that worked for me is:
At an elevated command prompt, type slmgr.vbs . If you type it without parameters it will give you a help window, showing the parameters. Be patient, it ran slowly for me. What I did was type in slmgr.vbs -ipk your-MAK-activation-key . After a few seconds I got the response that the product key was successfully changed. I then typed in slmgr.vbs -ato and after a few seconds received the message that the product had been activated.
Good Luck
