For Windows XP the drivers are already installed and after connection you should be able to see "R/C" in Control Panel>Game Controllers.
For earlier versions of windows see below:
1] Connect the interface to the PC via the A to B USB lead.
2] The PC will show a box saying 'New hardware Found', R/C USB Joystick and then the Windows 'Add New Hardware Wizard' box will appear refering to 'USB Human Interface Device'. - press 'Next'
3] Select 'Search for the best driver for your device. - press 'Next'
4] Uncheck all the boxes. Windows should already have the necessary .INF file. - press 'Next'
5] You should see 'location of driver C:\WINDOWS\INF\HIDDEF.INF (if not put your windows CD in the CD ROM drive and check this (step 4)). - press 'Next'
6] You will be prompted to load your Windows CD. - press 'OK'
7] Press 'Finish'
8] Go to Start>Settings>Control panel> and click Gaming Options. You should now see a new controller called 'R/C' or '4 axis 4 button Joystick' with status 'OK'.
9] Connect your transmitter if you have not already done so. Click on the 'OK' and click properties. You should be see the bars in response to your transmitter.
10] Now set up the interface to recognise the stick arrangement for transmitter. Transmitter Setup