Python virtualenv questions
In windows:
Press Windows (or Windows+R) and then type “cmd”:  Run the Command Prompt in normal mode.

cd C:\Users\user\Desktop\UserProjectName> pip install virtualenv
For Create a venv run this  virtualenv -p python3 venv
Activate virtualenv venv\Scripts\activate
It will look like this (venv) C:\Users\user\Desktop\UserDjangoProject>
Then run pip install -r requirements.txt
Show the installed package pip list
I'm using VirtualEnv on Windows XP. I'm wondering if I have my brain wrapped around it correctly:
I ran virtualenv ENV and it created C:\WINDOWS\system32\ENV. I then changed my PATH variable to include C:\WINDOWS\system32\ENV\Scripts instead of C:\Python27\Scripts. Then, I checked out Django into C:\WINDOWS\system32\ENV\Lib\site-packages\django-trunk, updated my PYTHON_PATH variable to point the new Django directory, and continued to easy_install other things (which of course go into my new C:\WINDOWS\system32\ENV\Lib\site-packages directory). 
I understand why I should use VirtualEnv so I can run multiple versions of Django, and other libraries on the same machine, but does this mean that to switch between environments I have to basically change my PATH and PYTHON_PATH variable? So, I go from developing one Django project which uses Django 1.2 in an environment called ENV and then change my PATH and such so that I can use an environment called ENV2 which has the dev version of Django?
Is that basically it, or is there some better way to automatically do all this (I could update my path in Python code, but that would require me to write machine-specific code in my application)?
Also, how does this process compare to using VirtualEnv on Linux (I'm quite the beginner at Linux).