bookmarks.html is the file you need, in the profile folder. This folder is.....
XP: c drive Documents and Settings\<Windows login/user name>\Application Data\Mozilla\
Vista: c drive Users\<Windows login/user name>\AppData\Roaming\Mozilla\
by default, these folders are hidden.
In XP click START then Run, then type %appdata% then OK.
In Vista, click START, then find the RUN command, and do the same as above.