I work in IT and I am bemused by those who think that having an antivirus application is a good substitute for a modern operating system in today's online environment.
On average, three new strains of viruses are being released onto the internet each second. Antivirus companies cannot keep pace.
Modern viruses are highly sophisticated packages constantly morphing and covering their tracks to evade detection. Some arrange to deliver themselves in separate parts and some carry their own antivirus modules to fight off other viruses so they have exclusive access to their stolen data payload.
Meanwhile XP, hailing from the turn of the century, does not even support Mandatory Integrity Control to isolate crucial parts of the operating system from applications.
Be nostalgic if you like but do stop pretending it is a wise choice to keep using XP in an online scenario.