For most people, browsing is an either-or proposition: they use either Microsoft's Internet Explorer or Mozilla's Firefox. But I'm betting there's a bunch of people like me who find themselves spending time in both browsers, often simultaneously.
The problem is, my list of Firefox bookmarks bears no resemblance to my collection of IE favorites. It took all of about five minutes to solve this problem.
Move your IE favorites to Firefox
Open Firefox 3 and click File > Import to start the Import Wizard. Choose Microsoft Internet Explorer and click Next. Uncheck all the options except Favorites (or retain them if you want to add your IE cookies, history, and Internet options) and click Next and Finish.

You can also export your IE favorites manually. To do so, open IE and click File > Import and Export to open the wizard. Click Next, choose Export Favorites, and click Next again. To export all your favorites, click Next again, or drill down the folders listed under Favorites and choose only the shortcuts you want to export before you click Next. Choose a name and location for your favorites file, but be sure to retain the .htm (or .html) format. Click Next > Finish > OK to close the wizard.
Use this file as a favorites backup or to move your list to a copy of IE on another PC.
Add your Firefox bookmarks to IE
In Firefox 3, click Bookmarks > Organize Bookmarks. At the top of the Library dialog box, click Import and Backup > Export HTML. Choose a name and location for the file (retain the .htm or .html extension) and click Save. Close the Library dialog.
Now open IE and click File > Import and Export > Next. Choose Import Favorites and click Next again. Click Browse, navigate to and select the bookmarks file you just exported from Firefox, and click Save. After you click Next again, select the folder you want to store the bookmarks in and click Next yet again. Finally, click Finish and OK.
Sync your Firefox bookmarks with Foxmarks
This import-export routine should suffice for people who use only one, two, or even three different PCs. However, if you would prefer to store all your bookmarks in one place or if you frequently browse on public PCs, an online bookmark service may be a better solution. The free Foxmarks add-on for Firefox lets you sync bookmarks on a number of systems and provides access to your shortcuts after you log in at the Foxmarks.com site.
And yes, the site works with both Firefox and IE.