I have XP-Pro, and an Alcatel USB speedtouch modem. I see the remove hardware icon on the taskbar at all times. When I plug in my USB card reader and double click on the icon, I see that two devices are now attached, (the modem and "mass storage device").
I select the just the mass storage device, and click stop. I then receive the message that it may be safely removed.
This does not effect the modem, which remains connected.