usb charging rates

[Ian Stephen]

Charging my Freerunner on a dual boot laptop.  Freerunner is running Qtopia 
from microSD card.

Under Windows XP, on Freerunner
cat sys/devices/platform/s3c2440-i2c/i2c-adapter/i2c-0/0-0073/charger_type
reports "host/500mA usb mode 100mA"

But under Ubuntu it reports "host/500mA usb mode 500mA"

Ran cat sys/devices/.../charger_type repeatedly while rebooting the laptop 
from Windows to Ubuntu and the charging mode changed from 100mA to 500mA very 
near the beginning of Ubuntu booting.

Does Windows not speak the same USB protocol as the Freerunner?
Can't all computer USB ports provide 500mA?

IanS