HTC DROID Incredible User Manual page 45

Disk drive
This mode is available only when you have installed a microSD card on
your phone. Select this mode when you want to use your storage card
as a USB thumb drive, and copy files between your phone's storage
card and your computer.
When Disk Drive mode is enabled while your phone is connected to
the computer, you will not be able to run applications that use the
storage card, such as Music or Gallery. For more information, see
"Copying files to and from the storage card" in this chapter.
Mobile Broadband Connect
When you do not have Internet connection on your computer, you
can select this mode to share your phone's mobile data connection
with your computer. For more information, see "Using Your Phone as a
Modem" in the Internet chapter.
If you do not want to show the Connect to PC dialog box everytime
you connect the phone to the computer, select the Don't ask
me again checkbox in the Connect to PC dialog box. The default
connection type will be used when you connect the phone to the
computer.
To check or change the default connection type and to show or hide
the Connect to PC dialog box, press HOME
Settings > Connect to PC.
Basics 
> MENU, and then tap