The older first and second generation Windows Phone devices, the majority of them running Windows Phone 7.5, do not have the same hardware profile as the newer devices, and because of that cannot run the Windows Phone 8 operating system.

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There will be few high-profile hardware launches at the congress (despite the 67, 000-crowd of visitors milling over the 240, 000 square meters of the new site).

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But if past Windows launches are any guide, Microsoft will help its cause by spending hundreds of millions of dollars on high-profile TV ads, viral whisper campaigns and "co-marketing" money for its PC hardware partners and the resellers who push Microsoft software to big corporations.

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