IE8 has the option to Import bookmarks directly from Firefox. I assume
IE10 can do it, too, though I'm not in the position to look right now.
In an IE10 session, click on "FILE" in the menu bar, it's on the
left, usually. Some way down the new list will be "Import and Export",
click on that. "Import from another browser" is the top one on the new
window, make sure that's selected. Click on "Next". Select "Firefox".
You can also select Chrome and Opera, probably all at the same time.
Then click on "Import". It will churn away for a while (or for years
if your FF BM file is anything like mine).
Eventually, sometime in the next millennium, IE shows yet another new
window telling you : "These settings were imported successfully" (no
full stop). Click on "Finish" and the window goes away.
Your Firefox Bookmarks are now copied to IE10's "Favourites" list.
This works for most IE's since about IE6.
Copying from IE to FF is just as easy.
"Bookmarks" on the menu bar.
"Show All Bookmarks"
"Import and Backup" (they just *have* to be different, don't they?)
"Import data from another browser", now I suspect FF knows which
browsers are on your box because mine does not offer Opera or Chrome.
I could be wrong because mine *does* offer Safari, which I don't have.
I didn't continue from there, as I don't want FF contaminated with
loads of IE linkies but the rest of the operation should be fairly
easy to follow.