I have one person here who uses a dual-monitor setup (Win2k with a Nvidia card).  Windows treats the two monitors like one big screen, so if you have an application set up to take up both monitors (full screen), a window that pops up in the middle ends up half on each screen. I our case, there are some settings in the Nvidia software that allow you to set defaults, but I have never been able to get it to not center things like the windows logon screen.  
I would think that if you have EVO set up to come up on one monitor, the logon screen would be in the center of that monitor, but it would depend how your OS and the graphics card handle it.
 
David