Firefox 4 also has built-in sync (of bookmarks, history, and some configuration stuff if you like), so not the best reason to switch :P Go to Preferences->Sync

Firefox 4 also has built-in sync (of bookmarks, history, and some configuration stuff if you like), so not the best reason to switch :P Go to Preferences->Sync to set it up. (It requires both a password and a sync key because they store all your data encrypted. The sync key is used to decrypt it client-side.)