April 8th is a date all CIOs will have circled with red pen in their diaries. That's when Microsoft's support for Windows XP expires, ending 13 years of enterprise dominance for Bill Gates' operating system.
Thousands of companies have grown hugely reliant on the OS, but with trends like mobility, the consumerisation of IT and virtualisation on the rise, the future of enterprise IT is possibly more varied than ever before.
The important thing isn't the big circle on the 8th; it's that a jagged red question mark isn't scrawled over the next day on the calendar.
The widely-advertised date comes at an odd time not just for Microsoft, but for the enterprise IT industry at large.
Microsoft is generally acknowledged as undergoing a period of revitalisation.
New CEO Satya Nadella has filled the seat at the head of the table not long after the tech giant's $7.2bn acquisition of Nokia, but also following ex-boss Steve Ballmer's admission that the enterprise giant had missed the boat on tablets and devices.
Perhaps partly as a result, the market looks very different to how it once did. Microsoft no longer has a stranglehold on the competition, and end users have dictated a shift to tablets and smartphones provided by the likes of Apple and Google, while the cloud space has many big players.
It leaves CIOs with lots of decisions to make over whether they upgrade to Windows 7/8, look into virtualisation, or even go more heavily down the BYOD route.
So what are the options available to businesses once XP support runs out? And will Microsoft play as large a role in their futures as it did 13 years ago?