A reader wanted to transfer some files from one PC to another using a USB drive. Many of the files were newer versions of files already on the drive. Our Helproom Expert explains the hassle-free way to transfer the files without losing data, and also how to replace the old files with new.

QUESTION I've been trying to transfer a large amount of data from one PC to another using a USB drive. However, Windows keeps reporting that some of the files are duplicated on the USB drive, and wants to know whether to replace them or create new versions. Windows recognises that some files have since been updated, but still lumps together these instances with the identical file cases. Therefore, I must manually specify my preference in each case. With many gigabytes of data to get through, is there a better solution? Jenny Wallis

HELPROOM ANSWER A simple way around this would be to create a new folder on your external USB drive and then copy all your data into it. This will leave the drive's original files untouched, and Windows won't report any conflicts during the file-copy process. It's always safer to do it this way if there's any risk of accidentally overwriting the wrong file.

Windows 7 also has a Replace command, which can be used to replace one set of files with another. The /U switch will instruct the command to replace only files that are older than those you are copying.

Using C as the drive letter for the files you want to copy and N as an example letter for your USB drive (replace these with your actual drive letters), open up a command prompt. Go to Start, type command in the search bar and click on the ‘command prompt' icon which pops up in the results.

This will bring up a command window. In this window type the following commands, pressing Enter after each:

C: (change to your source drive)
CD (where is the folder containing your files)
replace *.* N:\ /U /S (where is the path to the folder on your USB drive where you want to copy your files)

The command will overwrite only the older versions of your files. A list of which files have been copied is displayed onscreen.

We urge you not to use this method unless you're absolutely sure you don't need both copies of any of your files, and that you're sure the newer version is the one you want to keep and not in fact a different file that happens to have the same name.

See all How to articles. Get free tech support in the Helproom Forum.

Visit Windows 7 Advisor for more Windows advice.