Well I know a lot of people have been getting the 52140 error code when trying to get online with the Wii. Everything else works and the connection is good but for some reason you get 52140. Well my Wii has been working online for about a week. I think that is enough time to be sure enough that my solution works or not. I'm not sure if it will work for you but it worked for me
Go to start>run>cmd
Type "/ipconfig/all" in the command prompt
Locate your dns address; there should be two different ones there. i:e 220.127.116.11; 18.104.22.168
Connect your Nintendo USB Wifi Connector
Go to My Network Connection and right click the USB connection and go to properties.
Under the General Tab there will be a list of options look for Internet Protocol TCP/IP Highlight it then click Properties
Now, click Use the Following DNS Addresses
Enter your two in and see if your Wii will now connect online
I'm not sure if it will work for you but it wouldn't hurt to give it a try. I may have just been lucky. Please post a response and tell me your results. Also I'm using the Official Nintendo Connector not the Datel one.