Diese vom Mozilla Release Manager Asa Dotzler für das update auf FF 1.0.1 veröffentlichte Anleitung kann sinngemäß auch für das update auf FF Version 1.0.2, 1.0.3 und 1.0.4 angewendet werden.
Steps for upgrading from Firefox 1.0 to Firefox 1.0.1
Automatic Update (Windows only)
Windows users1. Before beginning the update, be sure to complete any work you're doing in Firefox 1.0 and close any extra tabs or windows you may have open.
2. If you see a small red icon update icon on the right end of your menubar, click that. If you don't see the icon, then follow these steps:
1. Go to the Tools menu on the menubar and select the Options... menu item.
2. In the Options window, select the Advanced icon.
3. Scroll down to the Software Update section and press the Check Now button.
3. You should see a Critical Updates (1) item and a checkbox with the label Firefox 1.0.1(en-US) Software Update. If you do not see this, skip to the Manual Installation steps below.
4. Press the Install Now button.
5. Wait for the installing updates progress meter to finish
6. Follow the instructions in the Firefox setup wizard.
7. You will get one or possibly two Attention dialogs informing you that you must first close Firefox before proceeding with the install. This is normal. Select OK when prompted.
8. When the install completes, you may wish to uncheck the Use Firefox Start as my Home Page checkbox. If you leave this checked, your home page will be set to the default Firefox Start page.
9. Press the Finish button to complete the install.
10. To launch Firefox, double-click on the Firefox desktop icon or any other shortcuts you may have.
11. To verify that you have successfully updated Firefox to the 1.0.1 version, launch Firefox and select About Mozilla Firefox on the Help menu. Confirm that it says Firefox version 1.0.1.
12. At this point, you may wish to delete the Firefox Setup 1.0.1.exe file from your desktop. Should you have problems at any time during the automatic update, you can use this file to run the manual install. See the Manual Installation steps below.Note: there are a few issues with automatic update which we hope to have corrected by the next release.
* We do not clean up the Firefox 1.0 listing in Add or Remove Programs. Do not attempt to uninstall the old Firefox 1.0 from Add or Remove Programs. That will uninstall your updated version.
* When update is completed, the installer file is left on the Windows Desktop or default download location. Feel free to delete this after you've completed your install and verified that Firefox 1.0.1 is working.Manual Update (All Platforms)
Windows users1. Visit http://www.mozilla.org and click on the Free Download link and select Save to Disk in the resulting dialog.
2. When the download is complete, exit Firefox 1.0 by selecting the Exit item on the File menu.
3. Go to the Control Panel, double-click on Add or Remove Programs, and uninstall Firefox 1.0. This will not remove your Firefox bookmarks or other settings.
4. Locate the file Firefox Setup 1.0.1.exe which is either on your Windows Desktop or the folder you set as your default downloads location.
5. Double-click on the Firefox Setup 1.0.1.exe icon and follow the instructions in the install wizard.
6. When the install completes, you may wish to uncheck the Use Firefox Start as my Home Page checkbox. If you leave this checked, your home page will be set to the default Firefox Start page.
7. To launch Firefox, double-click on the Firefox desktop icon or any other shortcuts you may have.
8. Verify that you have the new version by selecting About Mozilla Firefox from the Firefox menu. You should see Firefox version 1.0.1.
9. At this point, you may wish to delete the Firefox Setup 1.0.1.exe file from your desktop.Mac users
1. Visit http://www.mozilla.org and click on the Free Download link and select Save to Disk in the resulting dialog.
2. When the download is complete, quit Firefox by selecting the Quit Firefox item on the Firefox menu.
3. Double-click on the Firefox 1.0.1.dmg file.
4. When the disk image has been opened and mounted, drag Firefox into your Applications folder.
5. When prompted to overwrite the existing Firefox, press OK.
6. Launch Firefox and verify that you have the new version by selecting About Mozilla Firefox from the Firefox menu. You should see Firefox version 1.0.1.
7. At this point, you may wish to drag the Firefox 1.0.1.dmg file and Firefox disk image to the trash.Linux users
1. First check with your distribution to see if they are offering the Firefox 1.0.1 update.
2. Ensure that you have sufficient permissions to install to the same location as your Firefox version.
3. To install from Mozilla, visit http://www.mozilla.org, click on the Free Download link and select Save to Disk in the resulting dialog.
4. Find and extract the firefox-1.0.1.installer.tar.gz file, (probably located on your desktop or your default downloads directory.) This will extract the files to a folder called firefox-installer.
5. Open the firefox-installer folder and double-click on the firefox-installer script to run the installer.
6. Follow the instructions in the Firefox install wizard, selecting your previous Firefox install directory when prompted for the install location.
7. Launch Firefox and verify that you have the new version. Select the About Mozilla Firefox item on the Help menu and confirm that it says Firefox version 1.0.1.
8. When the install is finished, you may wish to delete the firefox-1.0.1.installer.tar.gz file from your desktop or home directory.Note: Not all localized versions of Firefox 1.0 have updates available yet. You can determine if your version has been updated by visiting the Download Firefox page. You will not be prompted to update to 1.0.1 until an update for your language is available.
http://piercedotzler.com/asa/update.html
Gruss 
ps:
Die deutschsprachigen Versionen gibt es hier
http://www.firefox-browser.de
andere Sprachbersionen hier:
http://www.mozilla.org/products/firefox/all.html
Windows fragt gelegentlich, ob übrig gebliebene Bestände des Programmverzeichnisses vollständig gelöscht werden sollen. Diese Frage mit "NEIN" beantworten, denn da befinden sich Deine Plugins und Searchplugins
