This is a nice find that I came across for Windows Vista. It is a windows Sidebar Gadget and is available from Add a Gadget http://addgadget.com .
The item I tested was The Wireless Network Meter V3.0. See the screen shot below.
I have this gadget at the top of my list. It shows me which wireless network I am connected to as well as other items like my ip address, the public ip address I am connected to the internet with, a way to lookup my ip location geographically, and wireless signal strength. It also has some nice statistics on my network speed both up and down. It even shows a real time graph of network traffic.
It is very easy to install. Just download the single zip file, extract and double click the file to install. You can then go to the options screen and select the NIC that you would like it to monitor.
I find that I look at this gadget all the time. It has a nice UI that goes well with my other Windows Gadgets. I highly recommend this gadget to any Microsoft Windows Vista user using the sidebar that like to keep tabs on network info.
For more of my product reviews please click here.