USB slower on Vista than Ubuntu

Are you sure that the speed difference is from the driver? E.g. have you stopped the virus scan software and then tested the speed? Usually stopping virus scanning is not a good idea, but in case it is your stick and you just want to test the speed, then stop the scanning of file accesses and re-test. This should give you a speedup of about 2x. If not, then I agree, you should check for the chipset drivers. USB is not a separate driver, e.g. in my motherboard USB is inside the motherboard drivers.