We got this monitor when DS was born - a basic sound monitor. It works great, we had no interference and listened to his sound machine all night - which I like. http://www.amazon.com/Fisher-Price-Sounds-n-Lights-Monitor/dp/B000WU9CYI
We stopped using it when we switched him to a toddler bed, a friend gave us a video monitor. I LOVE having the video monitor but could definitely live without it. I would have been happy with the sound monitor. I think a few posts below there was a thread about video monitors - a lot of ladies had the same one as me and liked it!