or Start > Run > type "dxdiag" then wait till it loads..
and u can go to the Display tab to view ur graphic specs (note: which are not relevant in this Photoshop problem)
or, Start > All Programs > Accessories > System Tools > System Information
this System Info gives u the actual size of the RAM modules, while the other two tell u the total size minus the amount shared for graphics. Don't worry if you dont understand... Im just in the mood of writing.
Also, the GHz / MHz shown in comprops.JPG is the speed at which it is operating when you click on Properties... i.e. if its a laptop running on battery, it may not show the max speed. again, dont worry about this.