Search File for String Value

Hi!!  Hopefully somebody out here can help this newbie out.  I'm trying to create a webpage that when the user clicks on a button it goes out and reads from a text file and searches for 10 different strings.  It then returns either a true or false if it found each string.  I then would like to display a certain image for each depending on if it returned a true or false value.  Any help would be GREATLY appreciated.

Coce thanks for your reply!!  I was able to read in a file and search for a string.  Only thing is it returns a value as it searches throughout the entire file, so i get 100-200 statements saying found or not found.  How can I only return "one" value either yes the value was found(either 1 or 100 times) or no the value wasn't found.

Thanks to anyone who can help.  Sorry I'm still a rookie.

Below is the code:

<%
 Dim aString
 aString = "RDO0410"
    Set fs = CreateObject("Scripting.FileSystemObject")
    filename=server.mappath("/MyWeb/aobfsts.txt")
 Set readfile=fs.OpenTextFile(filename,1,False)
    Do until readfile.AtEndOfStream
        myTextFile=readfile.readline
  if instr(myTextFile,aString) <> 0 then
      response.write aString & " was found"
  else
      response.write aString & " was not found"
  end if
    Loop
    readfile.close
    set readfile=nothing
%>