The easiest way to do it would be through Firefox itself.

Click "Bookmarks" then "Organize Bookmarks".

Then "Import and Backup" at the top of that window.

Then you can press "Backup" to create a .json archive that can be imported into another Firefox to restore you bookmarks. To import a .json, proceed to the same location in the new Firefox but press "Restore" and pick your file.

You can also export the HTML of your bookmarks in addition, if you want to have another option. Obviously, you use the "Import HTML" option on your new browser to import such a file.

Excuse me, I have misread your post.

Instead, you can pull the data from your old profile on the slave drive.

To locate the profile, follow these instructions.

http://support.mozilla.com/en-US/kb/profiles

You should be able to import the latest .json from the bookmarksbackup folder in your profile.

You might also find the following page extremely useful.

http://support.mozilla.com/en-US/kb/Recovering+important+data+from+an+old+profile#Bookmarks_and_Browsing_History

Sorry about the split up and confusing response. Clearly I have had enough tech support for tonight.

See also http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox

Thanks Bug Follower. it worked. Phew!

Something tells me simplifying this job for novices like me would be a good feature for the programmers to add.