FirefoxPortable as default browser
When using FirefoxPortable as your main default browser in Windows XP, various registry settings are necessary for Windows XP to recognize it. Unfortunately, Windows provides setting the default browser only for installed programs. With the following tool you can manipulate the registry. Download and run the executable, then indicate the path to FirefoxPortable.exe.
Note that the drive letter where FirefoxPortable resides on must be consistent, otherwise you need to register the path again (e.g. when using a USB stick).
(modified 2008/09/06 by bco)