Just to clarify - you do NOT want IrDA devices as these do not generally work as Infrared receivers.
The USB-UIRT is what you want or you can build a homebrew based serial adapter (for a few dollars/rand)
There are other devices that also work , look at www.lirc.org
I am using an iguanaWorks device at the moment but I have had to modify source code to get it working for now.
I just received my USB-UIRT. On the device itself it is written "Pat Pend". I thought it was based on (or the idea based on) an open source project.
Core/Hybrid: Foxconn N570SM2AA-8EKRS2H (has 2 network ports), ASUS EN6200LE, AMD-X2 4000+, 1GB DDR2-800, 500 GB SATA/300, DVD drive/writer, Sony XL1B3, BTC 9019URF, Gyro Mouse, Gyro Remote, USB-UIRT, MS Win XP Remote, ATI HDTV Wonder, HDHomeRun