You can switch users from the Windows Command Prompt without logging off—if say, you need to access folders or files for another Windows user account. Reader PiE writes in explaining the process.
1. Quit explorer.exe
2. Open Command Prompt
3. Navigate to C:\WINDOWS\system32
4. Enter the following command:
runas /user:*computer name\*account name explorer.exe
Make sure you are cognizant of which user is logged in because this process will not change the Windows theme when the user changes. Thanks, PiE!
Runas [Microsoft XP Professional Product Documentation]