I have a wireless mouse, too....and while I love the freedom from cords, I hate the way the battery goes dead. And usually when it is a crucial moment, and you NEED it to work!!! Grr. What I have found is that the name brand batteries (I use Duracell) actually last a LOT longer than rechargeables or cheap $1.00 batteries (mine doesn't have an off switch either). So I think it is worth the investment, just so the mouse doesn't go dead as often. Basically, I have found that rechargeables last about a week, cheap batteries for a month, and name brand batteries for 3-4 months.