Couple of useful shell extensions for doing this sort of thing
Link Shell Extension
can do it via drag drop. LSE even implements Symlinks on XP's, they are not 'reachable' via Windows utilities, Shinagl uses a 3rd party library. Don't be put off by LSE's apparent complexity, most of it is hidden by default, to get the esoteric features you have to enable them via preferences.
can do it via navigating with a standard Select Folder dialogue
I use both, they are free to use and free from drama.
There's another gadget called Symlinker
, which is a stand alone program that's sort of OK for one off tasks, like yours. I don't use it, but it seems to work, although I find it very confusing - IMO its UI has things in the wrong order - and it seems to have had hardlinks and junctions grafted into it in a half hearted way. It only works on Vista & W7.
The attached screen shots show LSE in action,
a metadata.db from a Calibre Library on drive D: to a folder on Drive C: I then did a right click drag/drop of the metadata.db from the Drive C: folder back to the Calibre Library folder on drive D: and got the context menu you see in the first screen shot.
After selecting Create Symbolic Link Here
I get what you see in the second screen shot. Note the icon for metadata.db in Calibre Quick has a green arrow icon overlay similar to a shortcut, which is my visual cue that its a symlink, and that its size is zero and the Link Target is the metadata.db on Drive C:
Calibre had no problem using a symlink metadata.db on Windows 7
I use the xplorer2 File Mangler - couldn't live without it nor LSE.