After working perfectly for the past 1.5 years I have had my 13" MBA, I suddenly had WIFI issues. Let me give a few details about my experience:
I suddenly had issues connecting to the internet (I was able to connect to the wifi, but could not load a webpage in less than 2-3 minutes if/when it loaded) at my home, but had no issues when connecting directly to my modem via an ethernet cable - thus, it was not a network card issue or an issue with my internet provider.
After that, I had suddenly begun having issues connecting to the networks at my office and school...which is when I began to get frustrated.
See my answer below for how I resolved this issue.