Yes, you can.
However, results with this sort of thing depend on audio and speech quality, and above all, on training the software.
If iListen is well-trained to the speaker on the tape, then conversion of audio files to text is painless and simple. A customer of mine uses it to convert material he dictates into his little portable recorder into text and is very pleased.
If you plan on using it to transcribe different speakers (such as various speakers at conferences, or a panel discussion), you're probably better off just typing it out or paying a transcription service.