hi,
I found some informations for you.
".DS_Store is a Mac OS X metadata file providing information for a folder. It contains information on how tall/wide the window should be when Finder opens the folder, its viewing mode, and things like that. If a folder contains no .DS_Store, it will use the System Defaults and then create a new .DS_Store file to keep track of any changes users make. Every time you resize a finder window, it gets saved in .DS_Store, so that next time you open that folder, it will look the same."
".DS_Store files are invisible but, if you copy a folder under OS X to a disk and then open it in Mac OS 9, Windows or Linux you will see the disk full of .DS_Store files."
So, if you delete it, of course it will be back. 🙂