Is your Windows 7 32bit or 64bit?
If it is 32bit, then go to the Drivers download page and do not select the web based installer. Select the PCL or Postscript listed lower on the page.
After you extract the driver files, simple unplug the USB cable from your PC and then plug it back in. If you get prompted for the drivers, then browse to the extracted location. By default they are extracted to c:\xerox\[your printer].
If the OS is 64bit, you can use the Vista x64 driver (again, dont choose the Web Based installer) as the Vista driver is the same.
If you using a laptop, please make sure that you are connecting the printer directly into the laptop and not a docking station or port replicator.