turning off the radio means the phone will not make or receive calls or data.
it is useful for airplanes where phones are not permitted...
or if you are in a really bad cell reception area...the constant searching for signal eats battery...i turn it off when i go into the mountains where there is NO signal to conserve power...
to turn off the radio go to manage connections>turn of all connections... (to turn it back on just click it again...)
the button on top of the curve will put the phone in standby mode...which means the screen and keyboard will turn off and save power..
you will still receive calls, emails, data, etc and you will be notified as usual...
Standby does wonders for your battery life. I didnt even know about standby until a few days after i got my curve. When i began putting my bb in standby when not using it i got almost an additional day of usage before i had to charge. You will also notice that when youre charging your battery, it will hit 100% quicker if you are in standby. I tend to do this when i goto bed, put the phone in standby and plug her in..