There is a little known trick in PDM Workgroup for linking to an external file, such as a datasheet or PDF archive.
Here's how ...
*) Open a SolidWorks session, and 'pin' the task pane (be sure and set it to the PDM area to see vault)
*) Browse to your file using Windows Explorer
*) Right-click the file and select 'Create Short Cut'
*) Drag the shortcut to the SolidWorks task pane and drop it in the desired vault location
*) Delete shortcut from Windows Explorer
Now you can 'check out' the link and it it will immidiately open that file (from outside of the vault of course).
I like to drop it on top of related files so that they become 'attached' to them. I also like to keep the 'Shortcut' name, although you dont' have to.