Create your own templates
See these tutorials at Indezine:
And if you use PowerPoint 2003, Microsoft has a Template Creation Wizard that might be the kindest, gentlest way to get started making your own.
Where should I store templates?
Whether you create your own templates or receive them from elsewhere, you need to store them where PowerPoint can find them.
If you use Windows Vista and PPT 2007, put them here:
C:\Users\[Your User Name]\AppData\Roaming\Microsoft\Templates
(substitute your user name for [Your User Name] above, of course)
On WinXP and PPT 2003, use:
C:\Documents and Settings\]Your User Name]\Application Data\Microsoft\Templates
And generally, if you open the template file in PowerPoint then choose File, Save As and choose Template from the "Save as Type:" list, PowerPoint will automatically choose the correct template folder for you.
This will make the templates appear in "My Templates" or "New From Existing" when you choose File | New in PPT 2007.