let's talk online has tested many products for digital language teaching. Here is a selection of equipment with which we've had the best experiences.
Labtec Axis 342 Axis™-342 is a stereo headset for starters, which is excellent for voice over IP (Internet phone) more...
Labtec Axis 502 Axis™-502 is a stereo headset for intermediates, which is excellent for voice over IP (Internet phone). more....
Plantronic DSP 300 Digitally enhanced high quality stereosound. No sound card needed. more....
What do I need in order to learn a language Online? Check out a virtual classroom
Axis™-342 is a stereo headset for starters, which is excellent
for voice over IP (Internet phone) 
Axis™-502
is a stereo headset for intermediates, which is excellent for voice
over IP (Internet phone). 
Digitally
enhanced high quality stereosound. 
