Also, I added some code yesterday to add life bars above each units head (you can see it in yesterdays screenshot also). If anyone is interested, here is the code I used for the life bars:
life_bar.x = i->rect.x;
life_bar.y = i->rect.y;
life_bar.w = i->health * 2;
life_bar.h = 4;
SDL_FillRect(board_area, &life_bar, SDL_MapRGB(screen->format, 0, 200, 0));
i is an iterator of an STL list of units. Although the code is very simple, it looks great in the game.