1.25 billion Windows PCs 1.25 billion PCs 1.25 billion PCs 1.25bn installed worldwide, according to Microsoft 1.25bn installed worldwide, according to Microsoft 1.25 billion PCs over a billion Windows installations 1.25 billion PCs 1.25bn installed worldwide, according to Microsoft 1.25 billion Windows PCs over a billion Windows installations 1.25 billion Windows PCs 1.25 billion Windows 1.25 billion Windows PCs 1.25bn installed worldwide, according to Microsoft 1.25bn installed worldwide, according to Microsoft 1.2 billion computers 1.25 billion Windows