Now I had an opportunity to upgrade the USB slots to the latest 3.0 standard, and that has made more of a difference than I had originally anticipated.
The card was immediately recognized by my system, but only as a 2.0 USB standard. I installed the additional drivers that came with the included CD, and after that the card worked as advertised. I only have a handful of external USB 3 accessories (including a USB 3.0 HDD), but the card worked perfectly with all of them. The transfer speeds were quite noticeable faster, but I haven't really benchmarked them.
The reason why this card is particularly useful in the media center is a) helps with the playback of large video files directly from an external HDD, and b) USB 3 allows you (with appropriate add-ons and software) to use it to for additional monitors and TVs.