Another possible solution...

#!/usr/bin/perl

use strict;

my @array;
while( <DATA> ) {
    push( @array, $1 ) if ( /^(Include:\s.*)/ );
}
print @array;

__DATA__
Client/HW/OS/Pri: natsciexevs19 PC WindowsNET 0 0 0 0 ?
Include: Microsoft Information Store:\SG1
Include: NEW_STREAM
Include: Microsoft Information Store:\SG2
Include: NEW_STREAM
Include: Microsoft Information Store:\SG3
Exclude: (none defined)
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