Bitmeter II

Bitmeter is a bandwidth meter, it allows you to visually monitor your internet connection by displaying a scrolling graph that shows your upload and download speed over time.

If you spend a lot of time online, especially on file sharing networks such as BitTorrent, Kazaa and eDonkey, then a bandwidth monitor is almost indispensable - giving you real-time updates on how effectively your connection is being used, and alerting you to any problems immediately.
Features include: Graphical and numerical displays of historical data, Web interface, alerts, stopwatch, calculator, transparent/float/click-through modes, 36-page help file, audio notifications, configurable color-schemes and many other options. Version 3.5.7 offers minor fixes and feature enhancements.
This network & Internet program is freeware, so you can download and use it absolutely free
BitMeter features:

Audio notification at regular (configurable) time intervals - different tones are played according to your current upload or download speed (tone boundaries are also configurable)
Audio notification each time a certain amount of data is transferred (uploaded, downloaded or both)
Animated System Tray icon shows upload and download speeds
Check for new version (with auto-check option and proxy support)
Select any combination of network cards to monitor or ignore
Configurable graph scale - set to any value, or set to auto-adjust according to your speed
Connection Speed Helper
Option to display current graph maximum on screen
Change units used in readout (Kb,KB,Mb,MB)
Change graph type (bar or line graph)
Interval bars with adjustable time period
Adjustable scroll interval (anywhere between 1 and 60 seconds)
Save favourite colour combinations for later use, or use one of the pre configured colour-schemes.
Configure System Tray tooltip information (including speeds and days totals)
Show or hide readout area, or adjust its font-size.
Auto-start option for current user, or all users
Manual and automatic backup options of configuration and traffic history information