I would have thought new leopard would have made this easy to switch these off at the flick of a button ...or switch.
You can't turn them off. They're
supposed to be there! That's how the OS keeps track of each folder window. Where you last left it, what size you had it last opened to, how the files were show (list, icon, etc).
What you want to do is hide OS X's invisible files so you can't see them. Go to the /Applications/Utilities/ folder and launch Terminal. Copy and paste in the following line, then press Enter.
defaults write com.apple.finder AppleShowAllFiles False; killall Finder
That's it. The .DS_Store files (and all other invisible items) will no longer be shown on your desktop.
I think I will back up everything first. anyway ... but then will the .ds store will be on those too???
Yes. But again, they're supposed to be.