In Windows 8, I am using a local user account. I don't have a Microsoft account at all.
Do I need a Microsoft account to use the Windows Store in Windows 8?
Yes you need to register at the Microsoft Store Online to use it and for that you need a Windows Live login. If you click "sign in" at the top of the store you are redirected to here and it requests explicitly in the page title "sign in to your Microsoft account"