Oh - you mean the "bolded" part?
"We should be good with XP right if we use a different friewall app like Zonealarm, a spybot cleaner, AVG antivirus software and use Firefox Mozilla with javascript/flash locked down?"
The answer is maybe - but less and less so as more patches are applied to existing and supported operating systems (Windows Vista, Windows 7 and Windows 8/8.1 for example) and those patches fix issues that Windows XP has (and will continue to have since it will not be patched) and people learn to exploit them.
It is not always the end-user's actions that get them infested/infected - sometimes it is their inaction.