I've just started evaluating Windows 8.1 - a clean install requires almost 1GB of updates already!!!
There's two things to be aware of regarding local and internet accounts.
At installation time, as mad jock says, one has to be careful to select custom rather than express settings to ensure that a local account is created.
Also, the first time you use one of the built-in apps, it will probably drag you through an account creation / logon process, that will actually replace your local logon account with your MS internet account. Unbelievable.
Yet another thing - the local account you (hopefully) created is the only admin account, as the built-in Administrator account is disabled by default.
So my recommendation to anyone who wants to remain sane is to initially install and configure Win 8.1 with a "dummy" local account that will be your backup admin account. Then enable the Built-in Admin account. Then create a local USER (not admin) account that will be your main user account.
SD