I've built a cap 3 point setup using IR LEDs from Radio Shack. They are RS model 276-0143 and spec as 5mm High Output IR LEDs, 1.2 Foward Voltage, 100mA Foward Current, 45° viewing angle. I sanded the domes flat to increase the viewing angle, and built the system with the recommended 24ohm resistor for a 6v setup (four AAAs).
My webcam is a Phillips model of which I have removed the IR filter and set it to manual control, redeuced exposure, turned off white balance, etc. 30 fps 640x480 video. Also added two strips of exposed film over the lens.
As the video below shows, the webcam software has no problems tracking the LEDs, but in FreeTrack the tracking jumps around occasionally even when my head is held still. This is nearly impossible to use in any game.
http://home.comcast.net/~phantoms/temp/VideoFT.mpg