You can get your specs from running the DirectX Diagnostic Tool (dxdiag).
Assuming you have Vista or Win7, click the Start button in the lower left of your screen, type dxdiag in the Start Search box, and Enter.
The leftmost tab (System tab) should show Processor: (GHz) and Memory: (RAM).
The Display tab should show video card information, like "Approx. Total Memory." Note that when they say you need 1GB of Video memory, that probably means shared memory won't work well.
Whether your video drivers support OpenGL or not will probably depend on your driver version. You can find your driver version from the Display tab of dxdiag and then ask Google if that version supports OpenGL or not.
Assuming the requirements listed at Adventure Shop are correct, Dracula 4 really is a hog for video memory. For comparison, Dracula 3 only required 64MB of video RAM. Even Sherlock Testament only required 256MB of video RAM as a minimum.