I went here: http://www.thinkbroadband.com/tools/dnscheck.html
Success! We detected your IP address as NN.NN.NN.NN and did not find an open DNS resolver running.
Did you get a similar green result, Congrats, you are not likely to be a zombie.
Re-check here: http://dns.measurement-factory.com/cgi-bin/openresolvercheck.pl
and here: http://myresolver.info/
polonus