I could never get Freenet to work through a firewall that I don't control.
Windows makes everything harder. I know Tor works fine under Windows. If your BitTorrent client supports SOCKS proxies, then just set it to use localhost:9050.
If not, you'll have to use something like tsocks on UNIX: SocksCap (
http://www.socks.permeo.com/Download/SocksCapDownload/index.asp ) or FreeCap (
http://www.freecap.ru/eng/ ). Pick one, then figure out how to get your BitTorrent client to use it.