GPS data read directly by PIC

Hey guys,

I'm a total micro-controller newbe and I just started my first project.

I have an GPS receiver which has a USB output.
Is it possible to connect this USB directly to the one of the PIC18F2550 
or do I have to take the way over RS232?

If yes, can you give me some starting hints and probably easy code 
pieces for programming, how to read this data?

Marry Christmas
Sebastian