Im now using steven hickson amazing voice command software. Im only using a very cheap usb microphone, its like a 5mm bit of plastic on the end of a usb connector. So the question is what and how good was the microphone you used?
I used an inexpensive webcam with built-in mic. It worked fairly well from about 10-15 feet (3-5 meters) away, but it was positioned directly under a TV, and whenever the TV was on it was completely useless due to the nearby noise.