I initially had difficulty in installing this and thought that I was going to be one of the people for whom it did not work. However, this is the way I eventually installed it on a Vista machine.
1. Attach the USB end to your PC but do NOT connect your printer.
2. Allow Windows to install device drivers automatically for an IEEE-1284 Controller. (you do not require the supplied mini CD)
3. Only then should you connect your printer and switch on. Windows should automatically install printer drivers but if necessary will ask for a location from you. (Download printer drivers from the printer manufacturers web site if needed).
4. This cable is quite short and you may be tempted to use a USB extension cable but mine would NOT work when using an extension cable, so I moved my printer nearer. This may be due to a poor quality extension cable but it demonstrates that that something as simple as this can make a difference.
So, to sum up, make sure you allow Windows to install drivers for the cable BEFORE you connect your printer.
Hope this helps.