OpenGL without a graphics card

Sure. Many software only implementations of OpenGL exist. Check out the Mesa project at http://www.mesa3d.org/ for one of the most popular. There are parts of the shading language not fully supported, and it tends to lag the standard a bit in general, but that is the case of all software API emulators. Its still very full featured and can be used in production code for many common uses.

Update This was many years ago, the link is not available anymore, and there are probably newer, better, builds now.

Yes, you can use MESA.

For your convenience, I've compiled it in both 32- and 64bit at:

http://dl.dropbox.com/u/9496269/mesa.zip

Simply put them where your executable file is located.