If you right-click the desktop you can select 'Screen Resolution' this will open up a control window (see pic). From here you can 'Detect' your monitors, select the individual resolution for each monitor and how the display behaves.
Display Behavior: Duplicate Desktop: This option will show the exact same image on both monitors. Extend Desktop: This option adds control to both monitors seperately (you will notice 1 monitor has only the background & no icons). To view things on the second monitor, drag the application (while open) to the second screen, the mouse can move between both. To view the app in full screen just maximise it once you've dragged it accross. Show desktop only on 1 (or 2): This is fairlt self explanitory, it will only show your display on the monitor of your choice.
Also, some 3rd party software may offer greater control over your monitors (read the intructions, normally in PDF format) but that part is out of my hands as i use laptop dual desplay.
Unfortunately i think not (someone else may know though), Windows needs to be booted but only once. You could try VMWare or any other virtual machine software and run the virtual machine within the extended desktop. Try searching this forum for 'virtual machine' and see what comes up.