According to NPD figures, the XBO has sold 1,391,000 units from January through August of this year, while the 360 sold 1,808,000 during the January-August period of 2006. That means the XBO was at that point trailing the 360 by 417k. Whether the gap narrows or widens depends on what the XBO numbers for September are. I guess we're still waiting on the usual folks at Neogaf to provide those.

Now, if you want to count total LTD sales, that actually favors the XBO as it had a much, much better launch than the 360. The XBO sold 1817k during Q4 of last year while the 360 sold only 607k during Q4 2005 (I do understand that the 360 apparently had shortages at the time). That gives the XBO LTD sales of 3208k as of August, while the 360 sold 2415k from November '05 to August '06. Of course, the original Xbox had a much better launch than the 360 as well, pulling 1422k in the Nov.+Dec. 2001 period. Hell, even the Wii U had a better U.S. launch than the 360. So, launch sales don't mean a whole lot in the long run.

I'm still waiting on PS4 and XBO data for my graph, but here's the graph as it exists right now, with non-Xbox consoles excised so we can compare just Xbox consoles:

Note that the original Xbox got a price cut in May 2002, whereas the XBO had Titanfall in March and Kinect was unbundled in June.