Yup we have a wireless network as well (entertainment box down at the tv, and dh's laptop use it). In fact that was the reason I was keen to pull it out of the box to see how it would go coz I thought if anything that would probably interfere. But it didn't seem to. I was surprised how well it worked right inside the office.. coz I was prepared for it not to work so well amongst all our equipment, but as long as it worked down in the kitchen etc. But it was good everywhere. We've also got 3 cordless phones around the house. Hope all these RF signals aren't going through my belly to bubby! :-k

Edit: DH just suggested you could try changing the channel on the wireless network before trying more monitors. That might fix interference from that.