Mine handles it great! Of course, mine has absolutely no lag in WoW or any other game for that matter as long as my ping and latency are low. I have the retail edge package with an ATI X800XL PCIE card, and that helps a lot. As for the game, it's a ton of fun! Haven't run into any problems yet on my desktop.
I have installed the game on my laptops so I can take them with me to work and on trips. My business laptop runs the game, but it can get choppy when moving around on the map. My personal laptop runs it just fine, but it also has a gig more memory than the business laptop. I would say that makes a big difference.