Have you tried:

#!/usr/bin/perl

use File::Copy;

my $original_file = '//serv123/logs/log1.txt';
my $new_file = "C:/Documents and Settings/user/desktop/newfile.log";
[download]

Many years ago when I had to use Windows I found Perl was happy to accept / as a directory separator. I'm not 100% sure it works with UNC paths but it certainly used to work with the likes of C:/Temp and was a lot easier than doubling up the backslashes everywhere.