[Zope] Upgrading Python and Zope

I'm intending to upgrade Zope from 2.6.2b3 to 2.7.3 but thought I might as well take the opportunity to upgrade Python from 2.2.2 to 2.3.4. Is there anything I need to watch out for? I notice that in the process of installing the latest Python it has installed in /usr/local/lib/python2.3 whereas 2.2.2 was installed in /usr/lib/python2.2, so whilst I have installed the latest Python, I haven't actually upgraded it. Should I reinstall it in /usr/lib? And how do I ensure that Zope is picking up the later version? -- John