Which Fonts folder? In X there are several.
If you use Classic at all, put them in the Fonts folder in "System Folder" so they are available for both systems, even if they don't work for 9. If you are the only user, or if you want them to be available to everyone, put them into /System/Library/Fonts. If you just want them available to yourself, put them into /Users/Your user name/Library/Fonts.