after trying the drivers provided in the .zip, i tried installing the latest usb serial converter from "http://www.ftdichip.com/Drivers/VCP.htm"
FTDI drivers are for older Arduino models only. The UNO uses an 16U2 chip which is not compatible with the FTDI drivers. You should use the drivers in the top level of the Arduino-1.0/Drivers folder. When installed, the Device Manager should show an "Arduino UNO R3" under COM & LPT ports.