Take inventory of the system after the installation to determine which files were not modified or replaced. Perform another full backup once the system is ready to turn over to the user. In previous upgrade processes, I've made a conscious decision to spend a significant amount of upfront time in planning. My goal is to ensure that any changes made to a system are as risk-free and painless as possible. With individuals and business wholly dependent on their systems, any delay or disruption can significantly affect the organization.
Trouble can also result if quality is overlooked.
It's far cheaper to minimize or eliminate the causes of poor quality than to try to filter out problems later. As I'm building my upgrade plan, I have to consider seriously the impact of this upgrade on the large collection of freeware that we are using. Although I've been using packages from various sources almost my entire career, the last several years I've seen a dramatic increase in both the amount of software and the pervasiveness of its use. In some cases, the package is essential for our users. It therefore is imperative that these packages are available in a 10.0 environment.