Windows 7 to 8 Upgrade

In response to your original question, unless you have an application currently installed which is incompatible with Windows 8 an upgrade installation from Windows 7 to Windows 8 will leave all of your programs, settings, and data intact. An extra step you could take to ensure as seamless of a transition as possible would be to run the Windows 8 Upgrade Assistant available here which will provide you with a compatibility report which will point out any potential issues with the upgrade process which require attention.

As for the suggestion to perform a clean installation and reinstall programs over themselves, I would not recommend this process unless you consider yourself to be an expert and can spare some downtime if something goes awry. It can be done, as is obvious by JackNaylorPE’s success, and indeed I have done the same, but the level of complexity is much higher than with a standard upgrade. To properly accomplish this process a few things need to be true.

• You need to know where all of your data is, including storage of settings or tweaks. Folder redirection can help with standard data locations such as the desktop, documents, video, music, etc. but you may also need to manually ensure that data such as Outlook profiles, bookmark data, and other such information stored under the AppData folder is located on your data drive.
• You need to know how each application installs and holds its setting data. Some applications hold their settings data in the registry, these settings will be lost and require reconfiguration; some applications hold their settings in files in the program root directory, these files may be overwritten by the installer when installing over itself; some programs hold their settings under the AppData folder, these files may need to be backed up and restored.
• You will need to know where each application is installed. Applications which were installed to a location on the data drive may be able to be overwritten, but applications on the operating system drive will be removed in the clean installation and will require reinstallation.

The data component of this is one small part which works fairly well, but even with the above method with programs which are installed on the data drive you will still be required to run the installation files for most if not all applications. The standard upgrade process will not require this as nothing will be erased; it also eliminates the large potential for human error with so many variables.

You can double check your upgrade path here on TechNet to ensure that it will indeed keep your programs as well as files, but so long as you are not changing architectures, such as going from 32 bit to 64 bit, you should be fine.