If you are looking to use it with an HTPC, you might also look at Flirc. I have used it with a Harmony on a Zotac ND-22 running Openelec.
It costs a little more than an inexpensive IrDA. Also, the Harmony and Flirc overlap somewhat in purpose. The Harmonys allow you to emulate many different remotes and chain commands together for commonly used tasks. Flirc allow you to use many different remotes, including the Harmony, to control your media center software by translating them into keyboard signals as if you pressed a key on a keyboard. Also, a portion of every sale go to cancer research.
The website is http://www.flirc.tv/.