Blender 2.5x with dual Python installs?

Stupid newbie question here. I did search the forum but could not find an answer.

I currently have Blender 2.49 installed, and also have Python 2.7 installed on my Windows machine. Everything is working fine.
I do software development with Python 2.7, so it is set as the primary Python in my system’s PATH environment variable.

I see that Blender 2.5x requires Python 3.x.

If I install Blender 2.5x, will it also install Python 3.x and alter my system’s PATH variable to point to it?
If I keep the PATH variable set to Python 2.7, will this prevent Blender from finding Python 3.x?

I want to play with Blender 2.5x, but not if it interferes with my python software development (I do not develop in Python 3.x because I use several critical Python modules that have yet to be ported from Python 2 to Python 3).

You don’t need to install python 3.x as it all come bundles in with blender. You shouldn’t have any problems.

Thanks! I’ll give Blender 2.5 a go, then.