What is .DS_Store file in windows
That file is a proprietary Mac/OSX system file that holds attributes/meta-data about the folder it resides in.
These often appear in file shares that are accessed over the network by a Mac user; but that's not the only way you can get them. You may have gotten it in an archive (ie: a Zip file perhaps) you picked up someplace, which was originally created on a Mac.
I run into these all the time in archives we get from our graphic designers.
You're safe to just delete it.
More info: http://en.wikipedia.org/wiki/.DS_Store
For additional information on preventing them, perhaps check out these SU questions and answers (and others like them):
- How to prevent Mac OS X creating .DS_Store files on non Mac (HFS) Volumes?
- Any programs for getting rid of .DS_Store files?