Windows 7: restore point and hidden controls

64 bit Windows 7 Home Premium
Installing an application can make changes to the registry that the user will have little or no chance of finding because some registry entries have no label or data recognizable by anyone but the software’s designer. Some of those registry modifications can remain if the software is uninstalled and may continue to have detrimental results. If a restore point from right before the install is invoked, will the registry unconditionally be returned to its before installation content or is it still possible for some residue of the application’s modifications to remain and continue to cause mischief?

Applications may create files outside their install folder and, at least in earlier versions of Windows, might make changes to already existing files, such as some .ini files. Are there system files in Windows 7 that might be modified by an older application such that the changes/additions might survive the uninstall of the application and then be problems to reinstalling the application?

An application has been uninstalled. The install folder and all know files not removed by the uninstall have been deleted. A restore point that was created before the uninstall, but after the original install of the application, is selected. Scan for affected programs is invoked. The scan lists the uninstalled application under programs and drivers that might be restored.
Is there actually somewhere that the uninstalled .exe and related files are stored, from which they might be restored, or is it only the application’s registry entries that could actually be restored?

I have a still empty primary partition on my Windows 7 hard drive. Is it correct that I could install a working earlier version of Windows into this partition, or would I have had to do some special preparation when I set up the disk or when I installed Windows 7?



I want that earlier version of Windows only in order to run some tests. If I then reformat that partition, will the Windows 7 system be fully back to its previous condition such that there is no slightest delay, and no user intervention required, whenever I turn on the computer?