Next Tuesday, thousands of Irish businesses will become exposed to a large increase in internet viruses and malware when Microsoft switches off its security support for Windows XP, still used by one in ten Irish PCs.
According to new figures from the web-tracking firm Statcounter, the number of Irish desktop and laptop computers using Windows XP now stands at 10.3pc, a marginal fall on the 10.8pc share in January.
However, many Irish companies and public sector bodies continue to use Windows XP machines for reasons that vary from 'legacy' software applications to lack of IT budgets.
Businesses that continue to use Windows XP face higher IT security bills, with premium cover available from Microsoft at a hefty fee.
In January, the Irish Government had to agree a €3.3m emergency payment to Microsoft to provide extra security cover for Irish Government PC systems that have not yet switched away from the Windows XP system.
The measure will provide several government departments with interim security support while IT managers upgrade computers to newer versions of Microsoft software, such as Windows 7 or Windows 8.
Banks and some large enterprises have also had to pay interim premiums for extra security cover while they upgrade their machines.
Over 80pc of Irish ATM machines use Windows XP as a back-end operating system. However, spokesmen for NCR, one of the two biggest ATM machine manufacturers, said that they believed ATMs would continue to work "normally" after April 8.
"Financial institutions that do not migrate to Windows 7 immediately will have plans in place to maintain the integrity and security of their systems," said an NCR spokesman.
"NCR has plans to support both financial institutions who do not immediately migrate their ATM networks, as well as those interested in upgrading their user experience through Windows 7."
IT security experts say computers using Windows XP are "inherently" more insecure than modern computer systems.
"Windows XP is 21 times more insecure than Windows 8," said a Microsoft spokesman. "We've been saying that this day is coming for many years. We would advise those who have not yet migrated to a newer Windows operating system to do so as soon as possible."