path - Full URI to a file on another machine in our local network?

On our small-business Windows XP network, I have a file in f:\MyDir\SubDir\text.doc

What would be the URI for that file while I'm on another machine.... if all I knew was that machine's IP address, and the file's path?

I thought it was something like:

\\192.168.10.20\f:\MyDir\SubDir\text.doc

But that can't seem to locate it. (I have full admin access to both machines)