You have lots of audio choices, and almost all of them are better than the camcorder’s built in mic.
If you just need an interview mic for a stationary subject a few feet from the camera, you can use a lavalier on the lapel, a handheld, or a shotgun mic on a boom pole manipulated by an assistant. For longer distances, use a balanced audio cable and get an XLR adapter box to interface the three pin XLR connection to the camcorder.
If you do event video, or just need fast setup/teardown, and/or camera or subject mobility, you need a wireless solution. There are many good wireless mic systems, starting at around $400 or so. Or, get a minidisc recorder or an iRiver solid state MP3 recorder, and a lavalier mic to go with them. You can sync up the audio from these devices with your video footage in post.
In almost every case, the key to getting good audio is to get the mic element up close to the sound source. The camcorder is almost always too far away for best results. Whether you accomplish this with a hardwired mic, a wireless system, or a separate digital recorder is up to you.
Regards,
Doug Graham