WinLIRC allows you to transmit and receive standard infrared remote control signals.
About WinLIRC
WinLIRC allows you to transmit and receive standard infrared remote control signals. This allows you to control your computer using almost any standard infrared remote control. It also allows your computer to control other equipment which uses these signals (stereo equipment).
WinLIRC is the Windows equivalent of LIRC, the Linux Infrared Remote Control program. WinLIRC (through version 0.6) was originally written by Jim Paris. Later releases are written and maintained on sourceforge.
Hardware requirements
WinLIRC requires a very simple IR detector connected to a serial port. Any serial hardware that works with the original LIRC will also work with WinLIRC. Note that the parallel port hardware, IRDA ports, and Irman are not yet supported by WinLIRC. WinLIRC also supports a variation on the serial port receiver, that has it's pins attached to the irDA header pins on the motherboard. The transmitter is simply an infrared LED and a current limiting resistor. You should easily be able to buy all the parts for the transmitter and receiver for less that $15.
A 166 MHz Pentium should work fine (slower Pentiums may work too).
http://winlirc.sourceforge.net/