Asking for a signed driver for Windows 7 x64 when installing by hand

 Whenever I run the PDFCreator installer, it all installs just fine. But whenever I try to add a printer using "rundll32 printui.dll" I am either told the driver is unsigned or if I don't give it a path to inf and just give it a driver name, it tells me it is unable to find the driver, even if PDFCreator is installed.

So I guess I have some questions. 

Why doesn't the PDFCreator installer give me the unsigned driver error? and how can I do that with my own installer?

If I can't not reproduce that behaviour, is there a way to make the PDFCreator installer put the driver in the system in a way that when I tell Windows to install that kind of printer it will automatically find the driver?