i hope someone can help me out here, i would like some help here anyone.

i want to build an infrared transmitter/receiver system to connect to my pc through the USB port. The Infrared transmitter/receiver device will act as a sensor system to detect any movements made at the doorway and send a signal to the pc, and the pc will alert me via an SMS.

So far i have the SMS part working, i would like to know what is needed to get such a signal to the pc via the USB and probably what is necessary for me to write drivers for this device.

However i have not much experience in the hardware aspect of computers.

Thanks in Advance.

you neeed a HID (Human Interface Device) developed.
This is a circuit board that plugs into the pc and is recognized as some kind of outside peripheral device by tthe pc. Like a camera, Game Controller,wireless mouse etc. I have worke as a hardware engineer since the 80's an have developed several HID's. I can do firmware development and harware design as well as set up contract manfacturing. Maybe can help.
Drop me a line if you would like to discuss it further