Yeah, im interested in a Mozilla solution, too ... If you try the above reg entries it starts Mozilla when you dubleclick a html file, but Mozilla asks whether it should become your default browser. I cant figure out which reg entry kills this notice.

I was just trying to create a .inf file for setting Firefox as default browser while I stumbled across this:

firefox.exe -silent -nosplash -setDefaultBrowser

It works with 0.10.1 at least.

Edit: Doesn't seem to work anymore anyway here's the inf:

[Version]
Signature=$Windows NT$

[DefaultInstall]
DelReg=Remove
AddReg=Browser
AddReg=StartMenu

[Browser]
HKLM,"SOFTWARE\Classes\.htm",,,"FirefoxHTML"
HKCU,"SOFTWARE\Classes\.htm",,,"FirefoxHTML"
HKLM,"SOFTWARE\Classes\.html",,,"FirefoxHTML"
HKLM,"SOFTWARE\Classes\.shtml",,,"FirefoxHTML"
HKLM,"SOFTWARE\Classes\.xhtml",,,"FirefoxHTML"
HKLM,"SOFTWARE\Classes\ftp\DefaultIcon",,,"%16422%\Mozilla Firefox\FIREFOX.EXE,1"
HKLM,"SOFTWARE\Classes\ftp\shell\open\command",,,"%16422%\Mozilla Firefox\FIREFOX.EXE -url "%1"""
HKLM,"SOFTWARE\Classes\gopher\DefaultIcon",,,"%16422%\Mozilla Firefox\FIREFOX.EXE,1"
HKLM,"SOFTWARE\Classes\gopher\shell\open\command",,,"%16422%\Mozilla Firefox\FIREFOX.EXE -url ""%1"""
HKLM,"SOFTWARE\Classes\http\DefaultIcon",,,"%16422%\Mozilla Firefox\FIREFOX.EXE,1"
HKLM,"SOFTWARE\Classes\http\shell\open\command",,,"%16422%\Mozilla Firefox\FIREFOX.EXE -url ""%1"""
HKLM,"SOFTWARE\Classes\https\DefaultIcon",,,"%16422%\Mozilla Firefox\FIREFOX.EXE,1"
HKLM,"SOFTWARE\Classes\https\shell\open\command",,,"%16422%\Mozilla Firefox\FIREFOX.EXE -url ""%1"""
HKLM,"SOFTWARE\Classes\ftp\DefaultIcon",,,"%16422%\Mozilla Firefox\FIREFOX.EXE,1"
HKLM,"SOFTWARE\Classes\ftp\shell\open\command",,,"%16422%\Mozilla Firefox\FIREFOX.EXE -url ""%1"""
HKLM,"SOFTWARE\Classes\FirefoxHTML\DefaultIcon",,,"%16422%\MOZILLA FIREFOX\FIREFOX.EXE,1"
HKLM,"SOFTWARE\Classes\FirefoxHTML\shell\open"
HKLM,"SOFTWARE\Classes\FirefoxHTML\shell\open\command",,,"%16422%\MOZILLA FIREFOX\FIREFOX.EXE -url ""%1"""
HKLM,"SOFTWARE\Classes\http\shell\open\ddeexec\Application",,,"FIREFOX"
HKLM,"SOFTWARE\Classes\https\shell\open\ddeexec\Application",,,"FIREFOX"
HKLM,"SOFTWARE\Classes\ftp\shell\open\ddeexec\Application",,,"FIREFOX"
HKLM,"SOFTWARE\Classes\gopher\shell\open\ddeexec\Application",,,"FIREFOX"

[StartMenu]
HKLM,"SOFTWARE\Clients\StartMenuInternet",,,"FIREFOX.EXE"
HKLM,"SOFTWARE\Clients\StartMenuInternet\firefox.exe",,,"Mozilla Firefox"
HKLM,"SOFTWARE\Clients\StartMenuInternet\firefox.exe\DefaultIcon",,,"%16422%\MOZILLA FIREFOX\FIREFOX.EXE,0"
HKLM,"SOFTWARE\Clients\StartMenuInternet\firefox.exe\shell\open\command",,,"%16422%\MOZILLA FIREFOX\FIREFOX.EXE"

[Remove]
HKLM,"SOFTWARE\Classes\http\shell\open\ddeexec"
HKLM,"SOFTWARE\Classes\https\shell\open\ddeexec"
HKLM,"SOFTWARE\Classes\ftp\shell\open\ddeexec"
HKLM,"SOFTWARE\Classes\gopher\shell\open\ddeexec"

BTW you can use the command mentioned above for both firefox and mozilla as default browser by using the command mentioned in one of the registrytweaks:

"%PROGRAMFILES%\Mozilla\mozilla.exe -silent -nosplash -setDefaultBrowser" respectively

"%PROGRAMFILES%\Mozilla\firefox.exe -silent -nosplash -setDefaultBrowser"

using additional the -setDefaultMail should set Mozilla as default mailer

HKLM,"SOFTWARE\Classes\FirefoxHTML\DefaultIcon",,,"%16422%\MOZILLA FIREFOX\FIREFOX.EXE,1"

If your like me, dont forget to change it to c:\Appz\Firefox\Firefox.exe"

and doesn't it have to have \\ instead of \ when you list a file in the registary?