I'm posting this because I wanted to charge my Motorola Razor v3 Phone from a USB port on a PC using one of those standard miniUSB cables, and you wouldn't believe how hard it was for me to find out how! I didn't want to do any special software imports or exports or communication with the phone - I just wanted to get my battery charged before it died! It was surprisingly hard to find the software to send power to the USB port for windows. These were the two solutions I came across.
Solution1: Install DriverTool.exe (which will add some drivers) and allow power to be sent to the phone when it's plugged in.
Solution2: Simply use UBUNTU (booted from the LiveCD or an installation) and plug in the cord. It automatically sends power to the phone, no drivers needed!