The WoW site is currently running a "skin" advertisement, an ad type which by nature runs off the edges of the screen in most resolutions, so the horizontal scroll was disabled or it would be showing unnecessarily all the time for most people. I tweaked it a bit to better handle when someone visits with a lower than supported resolution. If you're not seeing a scrollbar there currently just refresh the page (F5) and it should appear.
In any case, all of our sites (like many others) are designed with a minimum 1024x resolution in mind, so I'd highly recommend increasing your computer's resolution. (on Windows XP: right click on desktop -> click Properties -> Settings tab -> Screen resolution slider) If you're already at 1024x resolution or higher then you're probably zoomed in a bit - in Firefox the command to reset the zoom level to default is Ctrl + 0 [zero].