It's right. Install Firefox Portable to X:\PortableApps\FirefoxPortable. Install jPortable to X:\PortableApps\CommonFiles\Java. FirefoxPortable.exe will automatically configure Firefox to use the JRE in jPortable on launch. This requires the current FirefoxPortable.exe launcher (introduced in 7.0 and 3.6.23). If you use the upgrade within Firefox, you won't have the new launcher and it won't work. The current Thunderbird (current and legacy), SeaMonkey and Iron support jPortable automatically as well. Chrome (all 3 channels) will as well shortly.