problem with txt.gz files in emacs

[Vinay Adella]

hi everybody there,
        I tried to open a txt.gz file in vi, it unzipped itself and opened 
the txt file. But when i did the same in emacs its showing some junk
characters. Why isn't emacs doing that? Is the option disabled because
emacs opens tar files which vi doesn't.
        could anybody help me out with this.
thanks
vinay