If you want to read a range of values from your light sensor (as opposed to on/off) then you will need more than just the sensor itself. As Kenny says, a $1 uC can achieve this quite easily. The code could be written in minutes. Serial port (or USB/serial cable) would be easier than USB, though obviously not as "up to date". If it's not a commercial project then this may not be an issue. Even with USB there are plenty of sample projects for PICs/Atmel/etc that could be adapted quickly. If you just want an on/off (i.e. light/no light) sensor, then you could probably use one of the serial control lines (DSR or CTS maybe - see [9-pin serial pinout][1]) to interface directly. [1]: http://pinouts.ru/SerialPorts/Serial9_pinout.shtml