A big challenge
Although millions of people choose to upgrade their existing PCs, most people choose to get a new version of Windows preinstalled on a new PC. In the past that often had to do with increasing system requirements in new Windows releases, and the need to purchase new PCs with more power to run the new version. With Windows 7 however, we made a commitment to work on many more existing PCs by keeping system requirements low and maintaining compatibility. We’ve continued that commitment with Windows 8, so many of you with existing PCs can simply upgrade. Looking just at Windows 7 customers, there are currently more than 450 million PCs that will be able to run Windows 8, but we expect that many systems running Windows Vista and even Windows XP will also be eligible.
Support for these PCs running different Windows versions is a big challenge in terms of testing all possible upgrade paths, languages, service packs, architectures, and editions. When you think about it, it is a rather remarkable achievement that hardware designed for one OS can be supported on an OS that did not exist when the hardware was created, especially considering that connecting hardware to software is a fundamental role played by the OS.
There are always complexities involving hardware support. Sometimes PCs are equipped with peripherals that require updated drivers for Windows 8, and in other cases, for any number of reasons, a PC maker decides that a particular model or configuration is not supported on a new version of Windows. There are also complexities in getting software to work seamlessly upon upgrade, particularly utilities that hook into the lowest levels of Windows such as anti-virus, disk format and defrag, or virtualization. While we have a massive test and ecosystem effort, ultimately the final say on support on a new version of Windows for a PC, peripheral, or software package is determined by the maker of that product. Our commitment to keeping things running and bringing forward software is industry leading and continues with Windows 8. At one recent team meeting, a member of our team showed Windows 8 running Excel version 3.0, which is the 16-bit version of Excel from 1990!
Perceived as “difficult”
During planning for Windows 8, we wanted to hear from customers who chose not to upgrade to Windows 7 even though their PCs would run it. In 2010 we commissioned a study of how people make PC purchase decisions, and talked to customers in three global markets to find out more. While the list of reasons as to why a customer chose not to upgrade varied by market, we have received notable feedback that upgrading the PC was perceived as difficult. So even though many customers wanted to upgrade, the current setup experience might be something that just wasn’t easy enough to make them feel confident in doing so.
Read more at source - http://blogs.msdn.com/b/b8/archive/2011/11/21/improving-the-setup-experience.aspx