Hydra does more than crack passwords. Also, if you're getting connection rejected on a server OS that's patched, I'd say that's kind of normal if it has a firewall going, but if it doesn't, I'm not sure as my use of Windows Server 2003 is limited at best.

Try this though from your shell:

man hydra

The docs aren't that bad and the info on hydra on their website is decent enough to where it isn't terribly boring so just read up on it more.

Another thing you may find useful is IPSorcery and or Hping. They don't crack passwords but you can make your own packets.