Fist things to do in this current situation ....
Make sure you have backups of your irreplaceable data - documents, photos, music, videos - preferably to an external media, (HDD, USB, DVD). so that if the worst happens you will not lose this.
Enable the hidden (built-in) administrator account, temporarily, for emergency use if required, log into this account at least once.
My method for creating a admin/standard user system is as follows ....
In the existing admin account (first created account?), create a second admin account.
log into the new admin account set up password and other required settings when this account is set and working go into the users control panel and demote the original account to a standard account.
log into the original account and use for day to day use - if requested for credentials by uac give the password of the new admin account
This method does not require you to move any existing files or change any permissions.
When the system is operating to requirements make sure that the Hidden Administrator has a secure password assigned, once this is done set the hidden administrator back to disabled