Windows can use a file system called NTFS (XP Win2k and NT) to store information on a disk. NTFS allows alternate data streams. The file you see when you look at a Windows hard drive in Explorer is the default data stream but attached to that can be one or more alternate data streams that you cannot see. You can see with ADS tools but to the casual observer they are invisible. The really neat thing is that if you attach a file using an alternate data stream, the file size of the original file stays the same. To simplify: You can hide files by attaching them to visible files. This is great for the paranoid and people with things to hide but its also used by Windows indexing system to store thumbnails of image files. The stream is called '?Q30lsldxJoudresxAaaqpcawXc'. They I downloaded a program called 'Stream Explorer' and while looking at some .jpg files that I had created in Photoshop and used 'Save for web' on, I noticed these thumbnail alternate data streams. One .jpg which Windows reports as being 8400kb has 4 alternate data streams. The thumbnail stream is 8728kb. Its bigger than the actual image file! Out of 13 image files in a directory of 14 files, 4 of them had alternate data streams larger than the actual image. To prevent windows creating these data streams, go to this site and do what you're told by Microsoft http://support.microsoft.com/default.aspx?scid=kb;EN-US;q319300 By the way I also found a stream by the same name attached to an HTML file and that stream was almost 30% larger than the actual html file. Greg
