A couple of friends have said no need. Eventually I might want apps that aren't compatible with XP, but until then it's just a matter of security. One friend has said that if I have Malwarebytes (free software) and run it frequently I should be okay (but Malwarebytes' site indicates that it should be used in conjunction with a regular anti-virus device [can you recommend a good one, preferably free?]). Another friend said that virus creators would not be interested in targeting XP.
Or should I download a more recent version of Windows? The Microsoft compatibility test informed me that it should be possible to install Windows 8 on my PC, but then stated that it wasn't available for download in this country. So how would I obtain a download for Windows 7 or 8? What sort of price?
As others have stated have one anti virus - either Avast, Avira (which I use) or AVG. For malware blocking Spywareblaster. For Malware scanning etc Malawarebytes and Superantispyware. All free versions.