I installed perl on my windows workstation so i could manipulate some email related files... It's been a while since I wrote any perl, but I was able to write a quick script to split some VERY large files into smaller files that another process could deal with easier:

open(INFILE,$ARGV[0]) or die "Can't open $ARGV[0]: $!";

($filename,$extention) = split(/\./,$ARGV[0]);

my $linecount = 0;

while(<INFILE>) {
	unless ($linecount % 10000) {
		my $filenumber = $linecount / 10000;
		close(OUTFILE);
		my $outfilename = $filename."_".$filenumber.".".$extention;
		open(OUTFILE,"<$outfilename") or die "can't open $outfilename: $!"; 
	}
	print OUTFILE $_;

	$linecount += 1;	
}

close(INFILE);
close(OUTFILE);

I'm sure someone could one line this or better it in many interesting ways, but it did what i needed it to do.