Hi krama757,
last time I've used
'Arbaro' .
Its free. Only thing you have to experiment with the leaves. If you let it generate usual leaves you'll end up with a very nice tree, only drawback - it's nearly useless if you want to have more than it in real-time...looots of polys.
Make the leaves very big planes, let it generate only very few, export it and re-texture it in your favourite 3d-modeller (I used Blender).
As textures I tried .tga with some leaves and the rest transparent. Loaded and showed in Irrlicht quite well.
Oh - and used between 500 and 800 polys for each tree for getting an reasonable look.
If that's still too many for you I'd recommend 2 simple crossed planes with one tree mapped onto it or one plane as billboard.
This way is not as easy as with other Apps, but at least free
Hope it helps you,
Alex