After much trying (about 12 attempts) this worked for me. Albeit security wise not a great idea. 

Fresh Database called DotnetNuke

Add User

Properties

            Add COMPUTERNAME\ASPNET

            Permit in database role ALL.

Drop unzipped directory into c:\inetpub\wwwroot\dotnetnuke

Rename Release.config web.config

Change the default user from “dbo” to ASPNET in webconfig

Put in correct database location into the web.config directory. Run as "sa" user.

Kept these in web.config

    <add key="AutoUpgrade" value="true" />

    <add key="UseDnnConfig" value="true" />

    <add key="InstallMemberRole" value="true" />

Drop the SiteUrls.config into the root directory.

Set full permissions for ASPNET worker process on dotnetnuke directory, Set full permissions for NETWORK SERVICE process on dotnetnuke directory.

Set full permissions for ASPNET worker process on dotnetnuke\Config directory, Set full permissions for NETWORK SERVICE process on dotnetnuke\Config directory.

Set full permissions for ASPNET worker process on dotnetnuke\DesktopModules directory, Set full permissions for NETWORK SERVICE process on dotnetnuke\DesktopModules directory.

Set full permissions for ASPNET worker process on dotnetnuke\Portals directory, Set full permissions for NETWORK SERVICE process on dotnetnuke\Portals directory.

For some reason the permissions on my machine weren’t passing on through the dotnetnuke directory so when the install script ran it choked whilst trying to install the portal directories etc.

Hope this helps other newbies. p.s. its defo worth the effort.