File operations unit

[Alex]

http://www.wilsonc.demon.co.uk/d9miscunits.htm

It has

TFileCopier is a component that allows you to reliably copy groups of files.

Drop a TRunOnce component on your main form, and you will only be able to run a single instance of your application... It's OnOtherInstance event gets called if another instance tries to start, passing the command line parameters from the second instance.

and other units