And you need to be careful about so called duplicate and identical files. I am not sure what you mean by "duplicated carpets".

Software programmers for Windows OS's have a choice of using common 'shared' files, or their own files, when they develop their own software. The types of files normally shared are Dynamic Link Libraries, or DLL files, and these are generally to be found in the Windows\System32 folder. But if the developer wants to use his own .dll files, then they will normally be located in the folder where the software program files are stored. So, you may have a number of dll files of the same name, and the same version, scattered all over the hard drive, but identifying any that may be redundant is very difficult.

However, you are quite correct that there will be many files and folders that have not been deleted even though you have uninstalled the programs themselves. There are two main reasons for this, sloppy programming and user data.

Sloppy programming is where the software creator has also created an Uninstall procedure, (used by the software's own Uninstall.exe or by Windows' own Add/Remove Programs), but has failed to do it correctly. That means that whenever software is uninstalled, some folders and files are left behind.

However, and to be fair to programmers, a lot of software, (like games, anti-malware utilities, work related software like spreadsheets, databases, etc), create logs or user files, and it is not easy to forward plan uninstall procedures to take those into account.

The only sure way to remove software is to use either the software's own Uninstall file, (often found in the Start Menu > All Programs folder for that software), or use XP's own Add/Remove Programs applet, then hunt down any folders that bear the same name as that of the software you have just uninstalled, and deleting all those. Mostly they will be found in the C:\Program files folder, and very often there will also be folders in C:\Documents and Settings\{UserName}, (where {UserName} is the name of the account in which the software was originally installed), and the Start Menu. There may also be folders in other C:\Documents and Settings folders, eg for "All Users", or "Administrator", or other named accounts, or any combination of these. I normally use XP's Search utility to search for such folders.

It will be almost impossible to find all redundant files in C:\Windows or C:\Windows\System32 folders.

I hope that helps.

Mark