How to Manage Local Groups on Windows Home
Ever helpful, Microsoft provides a GUI interface for managing users and groups on Windows. Unless you have a Vista home edition or a Windows 7 home edition, in which case you can't find the interface to manage groups because it isn't there. You can however manage groups very easily from the command line.
Manage Windows Groups from the Command Line
Command Line in your Start Menu Programs so that you can right-click on it and choose 'Run As Administrator'
net localgroup /? net localgroup MyNewGroupName /Add net localgroup MyNewGroupName MyFirstUserName /Add net localgroup MyNewGroupName MySecondUserName /Add ... and so on
And voila. You can now set security on folders in explorer, and use your new group to grant access.
If your Windows permissions are not working after you've granted new permissions, the usual trick is to lock and unlock your session (Start Menu -- The Power/LogOff/Hibernate/Lock/Sleep button). Failing that, log out and back in again.