I believe that information is kept in the registry in
As always, before messing with the registry, it would be a good idea to back it up. Here is a good tutoprial on how to do that: ERUNT - How to backup and restore Windows XP registry, Windows Made Easy
To see what is there open a Command Prompt and enter:
reg query "HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\TypedPaths"
Mine currently has 25 entries.