Everyone's mentioning interference. Think I better unpack the monitor we got and check it all out.

Edited: We just unpacked the monitor and checked it out. Seems really good! No interference.. and we have a PLETHORA of equipment on. Loads of computers, the cordless phone base station etc (which the instructions said could cause interference). And it stayed very quiet, but could hear DH clearly in the baby's room. Worked all the way downstairs and out to the back yard too. Think we'll be happy with this one