I recently installed Windows Vista (build 5536). It’s nice, but I’m still not going to use it full-time just yet. But I wanted a way to share my profile for Firefox in Windows XP and in Windows Vista. So I installed Firefox and started doing a bit of research, and it is quite easy.

First, backup your profile. It will be in C:\Documents and Settings\username\Application Data\Mozilla\Firefox\Profiles.

In Windows Vista, either go to Start > All Programs > Accessories > System Tools > Run, Start > Run if you have it showing, or WindowsKey + R to show the Run dialog. Next, type:
X:\path to firefox\firefox.exe -p
This will load the profile manager, delete the Default profile.

Load the Run dialog again, type:
X:\path to firefox\firefox.exe -CreateProfile "default c:\Documents and Settings\username\Application Data\Mozilla\Firefox\Profiles\xxxxxx.default"
That xxxxxx you’ll have to find out by going to that folder. When you hit enter, you are done and should load up Firefox with that profile.

(If you are trying to find Application Data in Vista, it is X:\Users\username\AppData\Roaming)