Perhaps something like this (untested) code would work:

#!/usr/bin/perl -w
use strict;
my $dir = $ARGV[0];  # first command line argument
opendir D, $dir or die "can't open $dir: $!\n";

# for each file in directory:
my $file;
while ($file = readdir(D))
{
 # only process files called "* screen res.jpg"
 next unless $file =~ /(.*) screen res.jpg/;
 # but only process them if the corresponding thumbnail exists and is 
+a file ($1 is the base name)
 next unless -f "$1 thumbnail.jpg";
  
  # now do the family of renames.
 rename $file, "${1}sr.jpg"
  or die "can't rename \"$file\" as \"${1}sr.jpg\": $!\n";
 rename "$1 thumbnail.jpg", "${1}tn.jpg"
  or die "can't rename \"$1 thumbnail.jpg\" as \"${1}tn.jpg\": $!\n";
 rename "$1 8 by 10.tif", "${1}8b10.tif";
 rename "$1 4 by 6.tif", "${1}4b6.tif";

 # open the text file for write and close it again
 # to make a 0-length file
 open T, ">${1}.txt" or die "can't open text file ${1}.txt: $!\n";
 close T;
}
closedir D;
[download]

update: hmm, "teach a man to fish" vs. "give a man a fish"?
Added comments for clarification.