Oh my God, you're misinformed.
Ram means nothing to World of Warcraft. It has trouble exceeding 2 GB of Ram in fact. World of Warcraft relies 65% on CPU, 30% on GPU, and 5% on RAM. (Making those numbers up, but it's somewhere around there.) If you want to increase your World of Warcraft performance, you'll upgrade your CPU and your GPU. I don't know that much about AMD, but upgrading your MoBo and CPU should be incredibly cheap because their systems are incredibly cost friendly.