You can also activate the hidden Admin account via the Local Policy Editor (equivelent to XP's Group Policy Editor)...

Open the Policy Editor (via Administrative Tool) Navigate to Local Policies > Security Options > "Accounts: Administrator account status"... open the properties for the policy entry and enable. You then need to log into said account to set password. Benefit to this way is that when ur PC hits a jam and you need the Admin account, no need to wait around while Windows builds the desktop configuration