Unable to install Python 3.5 within Windows XP Professional

from python.readthedocs.io :

As specified in PEP 11, a Python release only supports a Windows platform while Microsoft considers the platform under extended support. This means that Python 3.7 supports Windows Vista and newer. If you require Windows XP support then please install Python 3.4.

the last windows XP Python build is 3.4.4 : https://www.python.org/downloads/release/python-344/ 3.4.7 (2017-08-09) is available as code source

Sadly, any version of Python past version 3.4.3 is no longer compatible with Windows XP. They stopped supporting it all together - see 3.5 install fails poorly on Windows XP.

While CPython 3.5 doesn't work on XP, there is PyPy, an alternative Python implementation that does work.
However, current version PyPy3.5 v6.0 doesn't yet support asyncio module, probably the most interesting part of 3.5 update.

2020 Update: PyPy supports asyncio since v7.1.1, but I'm not sure whether it still supports XP. Leave a comment if you try it.

May be a bug in the installer? Try Python 3.4.3 - https://www.python.org/ftp/python/3.4.3/python-3.4.3.msi

Or click on white space in the 3.5.0rc3 installer.