What you can do if you have have Windows XP
So you still have Windows XP. What now? There are three things you can do.
1. Upgrade your PC's operating system
If your computer is under five years old, it can probably upgrade to Windows 7 or Windows 8. Windows 8 costs around €100 to download from Microsoft.com. Bear in mind that not every computer can upgrade from XP to Windows 7 or 8: some might just be too old.
2. Keep using your old computer in a limited way
While all experts advise against this, not everyone will switch overnight. If you can't afford a new PC or operating system right away, there are still some things you can do to minimise your risk of infection.
"In this scenario, you should really try not to connect the PC to the internet," said Patrick Ward, product manager with Microsoft Ireland.
"If going online is unavoidable, at all costs avoid online transactions, or activities involving credit card entries, online banking and other sensitive information. This is the kind of stuff that you really don't want to be harvested."
Mr Ward said that continuing to use Internet Explorer on Windows XP was not a good idea, as it uses out-of-date security systems.
3. Just buy a new machine
This is the easiest option, but also the most expensive one. A new desktop PC (minus screen or keyboard, which you already have) costs from €300, while a new laptop costs from around the same.
For a budget laptop, the 15-inch Asus F55 (Windows 8; €340) or 13-inch Toshiba Chromebook (non-Windows; €300) are good bets.
For higher-end laptops, go for either Apple's MacBook Air (from €1,100) or Sony's Vaio Pro 11 (from €1,000).