If you don't plan on using it that much, then not really. Charging it on your computer is fine. But if you find yourself using it more, then an ac adapter would be a good thing, so you can charge it without having to turn on the computer.
I will be purchasing a Sansa e260 shortly. Do I need to get an AC charger also. I have an URGE music subscription and listen to my music mainly on my computer. I will be using MP3 player only occasionally. Would I be better off getting the charger instead of charging through USB on computer? Thanks