Best way to mirror folders

You could take a look at SyncToy from Microsoft. It's got a number options for copying data between folders - this page has a useful guide on it's use and explains what the various options do:

Now, you need to choose how you want to backup the information. You can perform the following tasks between two folders:

• Synchronize: New and updated files are copied both ways. Renames and deletes in one folder is repeated on the other.

• Echo: New and updated files are copied left to right. Renames and deletes on the left are repeated on the right.

• Subscribe: Updated files on the right are copied to the left is the file name already exists on the left.

• Contribute: New and updated files are copied left to right. Renames on the left are repeated on the right. Similar to Echo, except there are no deletions.

• Combine: New and updated files are copied both ways. Renamed and deleted files are ignored.

If these folders are on the same computer, then you can create a single folder and a symbolic link to that folder, known as a junction on Windows. This way you don't need to synchronise at all: the two folders are actually one single folder with two names, and hence are in-sync by definition. (Note that Windows does not support junctions to directories on remote shares.)

Or, if these directories are on two (or more) different computers, or maybe even different operating systems, maybe sign up for Dropbox? It's free for 2GB (up to 3GB with referrals). This will synchronise automatically, and also give you all other nice Dropbox features such as backup, revision history, online access and file sharing.

Dropbox recognises if computers are in the same network, for super fast transfer using LAN Sync, but even that requires an internet connection while (automatically) synchronising. And the folders you want to synchronise should reside within the Dropbox folder (which itself you can locate anywhere you want).

if you're using Total Commander, it's got all you would expect from a modern file manager, including folder synchronization and comparison.