What you need:
- To connect the DS lap counter to the Pc you need the DS racing connection cable like this one.
- If your computer don't have serial port then you will have to buy a USB/serial adapter like this one.
- For the traffic lights you can use a Phidget interface (http://www.pclapcounter.be/phidget_interface.html), the 0/0/4 and the 0/0/8 have relay on board , the 0/16/16 and 8/8/8 don't have relay on board.
- Pc Lap Counter (http://www.pclapcounter.be/buy.html)
PS:
For DS lap counter , take a look here: http://www.pclapcounter.be/ds_racing_ds-030_ds-300_ds-200.html