PC makers are finding ways to keep selling Windows XP despite Microsoft efforts to remove it from sale.

Dell, HP and Lenovo are exploiting loopholes in Microsoft's licensing terms to extend the operating system beyond a 30 June end of life date.

XP is being phased out in favour of Windows Vista which has, so far, got a lukewarm welcome from many firms.

The news comes as Microsoft boss Steve Ballmer hints that XP could live longer if enough customers demand it.