This circuitry allows you to control your computer with a simple remote, like the one you already use for your TV-set. It’s very useful when you want to control a DVD or an mp3 player without having to stay at the keyboard. Please note that this circuit is NOT IrDA compatible and it won’t help you to connect to your mobile phone or whatever IrDA device; it’s only good to control your pc with a standard remote control. I use it for VDR and now my pc is a full featured set top box connected to the television, capable to digitally record and replay satellite television, DVDs and every kind of digital content (mp3, divx). There are many softwares you can install to control this ciruit; for Linux you can use Lirc and for Windows you can use either Winlirc, Girder, IR Assistant or uIRC.
How to build a simple but cool IR receiver – [Link]