I checked on my Active State 5.22 installation on Win XP 32 bit and BigInt is already there; code below works fine without installing anything. haukex says BigInt also comes with Strawberry 5.22. Most likely cause of your woes is a botched installation of something that you didn't even need to install! I would uninstall your Perl, then re-install a fresh copy. If BigInt is there, you are done. If not, then report back with exact details of what you are doing and messages that you see.

#!usr/bin/perl
use warnings;
use strict;

use Math::BigInt;
my $ro=0;
print $ro;
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