Yes it is possible with Windows XP and most current graphics cards with "dual head". Indeed graphic designers and People who work with Video editing workstations do it all the time and people who connect laptops to external monitors can often use both instead of one or the other
If your card has a dual output ( usually for DVI ) you can put the DVI to vga adaptor on and connect a second monitor : the driver options for the graphics card will then allow you to extend your desktop over both monitors or have a duplicate of one screen. This option will be available in the settings under display properties which you get to if you right click on the desktop or go via control panel. It tends to be a simple tick and you can chose which of the monitors you wish to be your primary monitor
If you extend the desktop you can open the tutorial in one window and PS in another.
Of course it is possible to have 2 graphics cards on your system but that is a bit less tidy than a single one with dual head
In practice it is less complicated than it sounds!! I do it later and post an image!
Meanwhile have a look
here