Easy, but expensive.
If you want wireless on 360, this is your easiest option. There are a myriad of ways, involving bridging wireless routers but if you want the easiest results, then grab this product.

Good but now redundant
Bought this a while back, easy to set up, but what with the new format coming out soon, the 802.11n, leave this alone now unless you don't have the n standard.

Fantastic!
I plugged this little thing into my Xbox (Asia region) and once I powered it on, it asked me to configure it.
It found my network immediately, and connected to it.
Connections have been smooth, and streaming media from my computer to my Xbox has worked perfectly.
If you are thinking about this product, then stop thinking and get it. It is definitely worth it.

Great product, configured instantly, works perfectly

Great price
It works brilliantly, and I grabbed mine here for about 87 bucks, while it's nearly $170 in some places.

Easy to install too.