The Edimax EW-7811Un (V1.0A) works out the box on the Xtrend ET8500 running OpenViX build 5.1.013.

Looking online, websites say the EW-781Un runs on a Realtek RTL8188CU chipset, but on my receiver it seems to be working with the Realtek RTL8192CU driver. I'm not sure if the EU and US models run on different chipsets, and if my EU does in fact have a RTL8192CU chipset, while the US models have a RTL8188CU chipset, but it's the only reason I can think of for the discrepancy.