How would u be able to decript a password from "_vti_pvt/service.pwd"???
I'm probably going to get flamed for helping you, but...
It looks like Altered-DES, "UNIX-style".
Try downloading a passwd cracker like "John The Ripper" and put each username : password into the password format like:
username : password : 0 : 0 :anything here : /bin/bash