I have been helping a friend with setting up the User Folder. I noticed as I helped him, that several of his old library files had not been converted to Vectorworks 2010. This happens to me every time I update my version of Vectorworks. There is a solutions though, Vectorworks has a batch convert command.
Go to the Menu Bar.
Choose File > Batch Convert…
Choose the folder for the start location.
Choose the folder for the end.
This will convert all the files in the source folder and place them in the destination folder. This should let you covert all the library files in your old version of Vectorworks and place them in the the new location, for the new version of Vectorworks.