im so stupid, i deleted some files and folders from my windows xp pc and now i need to get them back,

i had some really good wallpapers and screensavers in them but i deleted them by mistake and now i would like to get them bac, how can i retrieve my deleted files that are not even in my trash bin

i know that the operating system just deletes the files but the files actually stay in your hard drive until they are over written by something else on the same location.

can you give me any software of advise that can help me get my files back