After some looking online I found (here) that the issue was related to conflicting pip installs (I have a version already installed for Python 2.7 and apparently this is not compatible with the version that ships with Python 3.4.
To get around this issue I simply de-selected pip from the install options shown below and the install went ahead smoothly:
Run installer again and select PIP installation.
If the PIP fails to install with the same error, you may want to check environmental variables using a tool like http://eveditor.com/ which enables to check whether they are valid. If you had another version installed before, you most likely have wrong PYTHONHOME and PYTHONPATH variables. Fix them by setting them to relevant paths. e.g. PYTHONHOME=C:\python27 and PYTHONPATH=c:\python27\Lib
You will then be able to run and install PIP.