Microsoft, bless them, are trying their best with their customary Fear, Doubt and Uncertaincy to imply that all XP machines will blow up/be pwned/hacked the instant next month's last update goes through. That's not quite the case. True, since XP shares a lot of code with more recent versions, so crackers will be able to reverse engineer security updates to find and exploit holes in XP - but that will take time. It will gradually become less secure over time - months to years - as more and more unpatched exploits become known. If you run XP behind a firewall - preferably a dedicated hardware firewall and ensure your browser an AV is kept up to date, your security problems will be minimised. I'd recommend using an up to date browser, preferably with Noscript.
I'll keep running XP on this machine for a while, but will likely install Windows 7 on it (the Windows 8 abomination is going nowhere near any machine I use!). But I expect to be using my SusE 13.1 box much more in future.