When I first got the World of Minecraft client, I didn't get the minecraft.jar first. So, I let the World of Minecraft client automatically get it for me. Thats where the trouble started.
It said I couldn't load the server list, and that the response code was 502. I believe this was because the Minecraft.jar it was getting is an obsolete version to the current World of Minecraft clients' version, thus creating the problem of not being able to load the server list.
I deleted everything, and I first got the World of Minecraft Client download, then made a World of Minecraft folder on my desktop, double clicked the archive and went inside to highlight lib, native, and World of Minecraft, extracted it to the World of Minecraft folder on the desktop. Then, I downloaded minecraft.jar from rapidshares, (google minecraft.jar) and the downloaded it to my desktop, put it directly into the lib folder, and it started to work!

So if you downloaded the .jar from the World of Minecraft client and did not manually download it from rapidshares this could be your problem. Delete the World of Minecraft client folder, and redownload it, then manually get the minecraft.jar from rapidshares and this will fix your problem if your getting the Response Code 502 error.