uTorrent is the smallest torrent client out on the net.

uTorrent is a freeware BitTorrent client currently for Microsoft Windows only. The entire program is a single 576 KiB executable (as of January 2007). It was designed to use as little of a computer's resources as possible while offering equivalent functionality of heavily featured clients, such as Azureus or BitComet. Its title is frequently abbreviated as 'uT' or 'uT' (as it is difficult to type 'u' using many keyboard layouts). uTorrent is written in C++.

uTorrent Features

• Configurable bandwidth scheduler
• Customizable search bar and icons
• Unicode support. It utilizes embedded Unicode support for Windows 95/98/ME, avoiding the need for the Microsoft Layer for Unicode which is several times the size of uTorrent.
• UPnP support for all versions of Windows, implemented without the use of Windows XP's UPnP framework.
• No advertising or spyware
• Customizable user interface design

Updates : uTorrent Updates