There is a way to get rid of them; found this post on an Apple site:
When you use network servers a lot and access them by SMB/CIFS, AFP, NFS, or WebDAV, you get confronted sometimes with files that have the name '._DS_Store' or files that starts with '._'. MacOS X puts them there automaticly.
To prevent Mac OS X from writing these files:
- Open the Terminal
- Type (or copy / past) defaults write com.apple.desktopservices DSDontWriteNetworkStores true
- Reboot the Mac
Note that without these .DS_Store files the Finder is not able to display al the file info (press APPLE-I) anymore...
Source: Apple.com.