Freeware application Visual Subst lets you mount any file on your hard drive as a virtual hard drive.
That means that you’ve got quick access to your most oft-used folders—no matter where they’re located—through a simple virtual drive. The drive shows up in My Computer, or you can navigate to it through the run menu or Launchy by just typing the letter name (e.g., b:\) and hitting Enter.
I have mounted my music directory as a hard drive. Its quite useful. And free too.