I start off by saying that cordless mouses are the worst thing ever created since, well maybe Internet Explorer.
another problem with cordless mouses is that they use radio signals. so even when they got new batteries they sometimes don't work, interfering with another signal or something.of course, this never happens with a mouse with a cord.
and last but not least, a mouse with a cord is easy to pick up when you drop it, whereas with cordless mouses, you need to pick it up by yourself. these are the reasons why I'm using my old mouse with cords right now.