I'm using a Windows XP laptop on which the network card had broken.
I thought, rather than spending £s on having it repaired, I'd replace it with an external solution. I loked into the USB-to-Ethernet plugs, but they looked too cheap and I wanted something a little more robust.
So I chose this adapter, which turns out to have been a very good choice indeed. I received the adapter, installed the drivers from the CD, plugged it in - and it just works.
The adapter is relatively sturdy, looks finished, and is really really easy to use. It's not given me any troubles at all since I installed it a few weeks back, and compared to what some of the other adapters cost, this is definitely not cheaper because it's worse - in fact, it's really good.
I can't tell whether it works on any other systems, but I recommend it highly to anyone using WinXP.