The new Microsoft OS currently code-named "Longhorn" will feature a graphics subset called WGF (Windows Graphic Foundation) which has the main objective of unifying 2D and 3D graphics on the Windows desktop. Nowadays, 3D is done using a Direct X subset, but all of this will change with "Longhorn."
Longhorn will also use 3D menus and 3D interfaces and will require at least Shader 2.0 compliant cards, so it will make the graphics card an important part of your PC. Believe it or not, your Windows performance will depend on the quality of graphics card you have. A faster card might draw something faster than a slower mainstream or entry level card, meaning that even some Office software might perform better if you have a faster 3D card.