Save (sync?) "I.E. Favorites" + "Firefox Bookmarks" AT THE SAME TIME?

I've spent the past 2 days reading dozens and dozens of websites & forums about

saving/syncing IE Favorites and FF Bookmarks -- but none of them seem to really

address my particular issue.

Right now, I am using IE, and save dozens of IE Favorites every day. However, I'm

considering trying out Firefox browser for a couple weeks, and would like any new

FF Bookmarks to AUTOMATICALLY be included with my IE Favourites.  Likewise,

while I continue using IE, I would like any newer IE Favorites to AUTOMATICALLY

add themselves to my FF Bookmarks. That way, when I finally decide between FF

or IE as the browser I'll forever use, all of my IE Favorites or FF Bookmarks will be

there, and UPDATED.

It seems like all the sites / forums are about syncing Favorites **OR** Bookmarks

across MULTIPLE computers, but that's not what I'm seeking. I want to save/sync

my Favourites **AND** Bookmarks on the **SAME** computer, and in REAL time.

Any help would be greatly appreciated.

Ones I've read about:  (Those with asterisks ** are apparently the most promising):

-- bookkit.com

-- bookmarkbridge.sourceforge.net

-- bookmarksync.com **

-- cometmarks.com

-- dotbookmark.com

-- foxmarks.com

-- lunarmark.com

-- open2go.com

-- syncbkmk.sourceforge.net

-- syncmarks.com

-- sync2it.com

-- tidyfavorites.com

-- xmarks.com  (whose literature, ironically, says nothing) **

-- zinkmo.com **

-- addons.mozilla.org/en-us/firefox/addon/plainoldfavorites/ **

-- addons.mozilla.org/en-US/firefox/addon/checkplaces/

-- kb.mozillazine.org/Sorting_and_rearranging_bookmarks_-_Firefox

and strangely enough:  Google Toolbar  or  Google Browser Sync **