What do you consider "too long"? I've left my Sansa c240 plugged in overnight to charge and have had no problems. Usually those types of batteries will accept a certain amount of charge and then no more (like rechargable AA and AAA batteries - you can leave them in the charger so they're ready to go). I doubt you'd be leaving it hooked up the computer for weeks at a time, so I don't think it's an issue. The Sansa also has the fortunate option of an consumer replaceable battery (it's very easy - I checked)

xarophti