Unfortunately, XP owners, the biggest body of Windows users, won't be able to do that. They'll have to wipe out their hard disks after backing up their files elsewhere, then install Windows 7, then restore their personal files, then re-install all their programs from the original CDs or downloaded installer files. Then, they have to install all the patches and upgrades to those programs from over the years.
Microsoft includes an Easy Transfer wizard to help with this, but it moves only personal files, not programs. This painful XP upgrade process is one of the worst things about Windows 7 and will likely drive many XP owners to either stick with what they've got or wait and buy a new one.The idea of having to wipe out my drive just to install Windows 7 makes me not want to buy Windows 7. I understand that XP is 8 years old but MSFT knows that many people dodged Vista because they thought it sucked. They should have known that these people were waiting for a new OS and wanted an easy upgrade path from their current system with XP to Windows 7.
Now the idea of wiping out every users hard drive just to install Windows 7 sounds like an idiotic waste of time. I guess this will lead to a lot of companies simply buying scads of new machines instead of trying to keep the old machines and upgrade them. Perhaps some of those companies might even think about buying Macs instead of new PCs costing MSFT some sales.
So in other words it is about time to go long Dell, HP, and other computer hardware makers because companies now have no choice other then buying new hardware. I still foresee some companies sticking with Windows XP until they are forced to change due to an end to XP support. They might even continue using XP after support ends rather then be forced to wipe out every hard drive in their company.
Now I understand why Lenovo and Samsung decided to push back the release of their Nvidia Ion Netbooks (the S12 and the N510 respectively) rather then release them in August. Imagine telling their early adopters that they had to wipe out their hard drives in order to buy the latest OS that came out in October. I would have been fit to be tied if that happened. In any case Microsoft screwed up again and it will cost them sales in the long run.