The beauty of SDL is that you dont need to knoe the underlying technology layer. Its all hidden from you.

(I tried to find a reference on the net to what I say next but couldn't find the original ref)
SDL uses DirectX 5 for 2D rendering (if it cant find it it then uses GDI or equivilent).

This seems to indicate its a bit old. However because it uses alternatives it means you dont need to worry about the correct drivers being in place which is what I have experienced on both DelphiX and GLXtreem.

SDL is really easy to use. Once I decided to look at it it took me less that 3 hours to have my first example program up and running. Less that 8 hours to have my first Library (S2DL) developed. Using that library I developed a puzzle game in 3 hours. (Including sound)