I've posted the first test of a fully Vista-compatible launcher. NSIS just added support for the manifest files required by Vista yesterday, so I created a new Firefox Portable launcher using this new feature. This should prevent both the elevated privileges required prompt on launch and the application failed to complete on exit. I'd like some other folks with Vista to test this out before I incorporate it into the next release.
1. Grab a copy of Firefox Portable (either 188.8.131.52 or 2.0 RC3) and install it somewhere. (Don't worry that the Firefox Portable setup requires elevated privs... this will be changing. If you're on a limited account, grab the zip file)
2. Grab the Firefox Portable 1.3.2 Launcher and place it in the FirefoxPortable directory alongside FirefoxPortable.exe.
3. Start it up with FirefoxPortable132.exe
It's a single line addition that causes NSIS to add the XML manifest file (see source) and it appears to be adding it correctly. I tested it on Vista RC2 and it worked as expected. Please give it a try and let me know how it works for you.