1680x1050 shrunk down to 1280x1024 will be blurry.

After you set to display in horizontal view, go into your WoW account that will display on the 22" monitor and change the video setting close to 1280x1024 res. This should help reduce the blurry.

If you use WoW Maximizer, you can also change the Account.wtf in the WTF folder.