New Mouse

I think i need a new mouse for both my desktop. It's a cordless mouse from logitech (it's already more than five years old and it's still working great). It has infra-red capabilities, so i can move my mouse from distances and it's still working. The problem is that it requires a battery to operate. Sometimes, i left my computer turned on when i go somewhere else (mostly because i'm leaving my download window open, either directly from browser or from torrent) and it still consumes the battery power and every 3 weeks or so i had to change the battery.

My laptop uses a normal USB mouse. I bought it because i am not used to use touchpad when working with laptop (at first. Now i'm quite used to it). Because i used my desktop mostly now (since i have moved back to my hometown), i'm thinking to switch between my desktop and laptop's mouse, so i can have two benefits:
1. I don't have to buy new mouse
2. I don't have to buy lots of new batteries, since i can use the touchpad most of the time (when i'm teaching) and only use the mouse when i need something that need a precision (for my laptop)

But after thinking for a while, i think i do need new mouse for backup. I don't have any spare at my house, so it might be a good idea to buy one.

There's another solution also that in my head, which is buying a rechargeable batteries and also the charger, so i can have them recharged all the time. Hm... will think of it tonight and decide it for tomorrow's plan