Python 3.2 is already installed on my computer but ArcGIS wants version 2.7

Hey there,

while trying to use the "Raster Calculator", I got the error message that Python 2.7 is not installed.
That is right, as while installing ArcGIS I decided not to install PYthon 2.7 as I already use Python 3.2 on my computer.

Is there a possibility to change the settings so that ArcGIS uses the 3.2 version?
I definately need the 3.2 version of Python for other university stuff. Can I have two different versions of Python on my computer at the same time?
Or any other solution?

I really don't know how to solve the problem and would be very thankful for any advice...

Thanks