PicoTorrent is designed to be a tiny, easy-to-use BitTorrent client with low memory usage for Windows (Vista and above). It is a free and open source P2P client application that's straightforward, light on system resources, well-designed and efficient.
Here are some screenshots to illustrate the features and user interface of this application:
FrostWire
Tribler
uTorrent
BitTorrent
qBittorrent