Free. Windows. If you're looking for a good BitTorrent client, try uTorrent. It has what other BitTorrent clients have, such as scheduling, bandwidth management, and Mainline DHT, plus extras like a unique protocol that detects and corrects for heavy traffic.
Free. Windows. UTorrent is a free, portable BitTorrent client that nevertheless includes most features common to peer-to-peer utilities, such as bandwidth prioritization, scheduling options, autodownloading of RSS feeds, and decentralized tracking through Mainline DHT.