Stephen - 45cm is a bit short and its a tad on the expensive side...
They are pricey, however 45cm is probably near the sensible limit of a USB cable without a hub to boost the signal.
Most of these cables work fine and basically map the usb connection to some serial port (eg COM9) for your application to use.
What you can probably do is make a shielded serial cable for the length you need and just use the USB portion for the last couple of feet to the laptop. I've used CAT5 cable for this in work over around 20 feet with no noticiable signal degradation.
  