Hi Adrian,
Welcome to Vista Forums.
This is caused by your settings in 'Folder Options'. These files are normally hidden, and they contain information about how to display the contents of a particular folder. These files are harmless, and if you delete them, Vista will recreate them automatically. In some cases, whilst deleting them won't do any harm, this will cause the folder to revert back to displaying its contents in the default manner for the content of the folder. To hide these files again, the easiest way is to click on the start orb and type 'Folder Options' in to the search box and press enter. Click 'View' and then 'Restore Defaults'. Click 'OK' to close the dialogue box.
Dwarf