Install multiple Firefox versions

In windows, to install multiple firefox versions do the following steps:

0. close all the firefox windows.
1. Install various versions of firefox in your system INTO DIFFERENT DIRECTORIES.
2. run the following command and create one profile for each version.
c:\Program Files\Mozilla Firefox\firefox.exe -profilemanager
3. Run the fireforx with -p
eg:
"C:\Program Files\Mozilla Firefox 3.5\firefox.exe" -p ff3_5
"C:\Program Files\Mozilla Firefox\firefox.exe" -p ff4_0

Now, you can open both the firefox versions at once.