what is the easiest graphics library to program in 2d
Allegro. Available for most OS's and very high quality. Giftware. Get the latest version here.
If you use the free compiler and visual development environment Dev-C++, you can use my graphical installer for Allegro. My site.
Allegro precompiled Installer for Dev-C++, MSVC, and Borland: http://galileo.spaceports.com/~springs/