Buy a quality brand of batteries like Duracell and Eveready. Those cheapo batteries like at RadioShack and bargain brands don't seem to last very long at all.
I buy an 8-Pack of Duracell AAs once a month for about $5 at WalMart and rarely ever use the whole pack each month. Use 2 ea for my cordless mouse (LogiTech). And I'm online alot. Worth it to me anyway.
Rick Wilson aka CorpRebel