If you are using the firefox as your Internet browser, then you can manage multiple firefox profiles in your system. And also you can able to share a single firefox profile between several OS which are running on a single machine. If you create that profile folder in a drive which is separate from the OS drive, then you don't need to worry to format the OS drive. And also there are several other advantages are available by having a separate profile from the default one. But my goal is guiding you to create a separate firefox profile from the default one rather than explaining those advantages.
Noramly the default profile folder is in the %APPDATA%\Mozilla\Firefox\Profiles\xxxxxxxx.default\ location in your hard disk.
Your default profile folder is named xxxxxxxx.default, where xxxxxxxx represents a random string of 8 characters.
%APPDATA% is shorthand for the C:\Users\< username >\AppData\Roaming\ folder (Windows Vista) or the C:\Documents and Settings\< username >\Application Data\ folder (Windows XP/2000), which depends on your Windows user account name.
Change the default profile
Step 1 : Close the firefox if is is running.
Step 2 : Open the Command prompt and type the path to the firefox installation dir by using cd command. [ Ex : cd C:\Program Files\Mozilla Firefox\ ]
Step 3 : Now type this command in the command prompt.
firefox.exe -ProfileManager
If it is not working type the following command.
start firefox.exe -no-remote -P
then the profile manager window will appear in the screen.

Select the create button and second screen will appear on the screen. There you can give the path of the new profile and name of that profile. There after save the changes by clicking the 'Finish' button.
Now you can able to load that new profile in a new location.