While the company said that it will continue to provide free security fixes for XP until 2014, any future bugs found in the platform will not be fixed unless customers pay for additional support.
Mainstream support for XP will end on 14 April 2009, over seven years after the operating system originally shipped.
However, the passing of the deadline will place Microsoft in the unusual position of no longer offering mainstream support for its most widely used product. Windows XP accounts for about 63 per cent of all internet connected computers, according to March 2009 statistics from Hitslink, while Windows Vista makes up about 24 per cent.
Windows XP also continues to be sold with low-cost mini laptops, otherwise known as netbooks, as Vista is too heavy on system resources for this level of hardware.
The key message, according to Microsoft, is that the company will continue to provide security support for XP users.
"We will provide critical security fixes via Windows Update for all editions of XP until 2014," said Laurence Painell, Windows marketing manager at Microsoft UK.
Microsoft's mainstream support includes problem resolution over the phone, and covers fixes for security and non-security related issues such as bugs and requests for changes.
Once Windows XP moves out of the mainstream support phase, customers will need an extended support contract with Microsoft or one of its channel partners to address any issues not related to security.
With a platform as mature as XP, this is unlikely to prove an issue, according to Microsoft.
"XP has been out a long time, so we would hope that there are not many issues that would require that level of support," said Painell.
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