asp.net MVC 403 error when deployed to IIS7.5

Today I had to deploy my test .Net MVC app to Win Server 2008, IIS7.5, but I kept getting a 403 forbidden error when visiting the site. It turned out that despite setting my app pools to use .Net 4.0 you have to register .Net 4 with IIS. I'm not sure if I've understood it correctly or got my terminology correct, but this command-prompt solution I found on StackOverflow sure hit the spot:

cd \
cd Windows\Microsoft .NET\Framework\v4.xxx.xxx
aspnet_regiis -i

Big-up to Michael Shimmins