DirectX actually works ok. At least the windowed test apps I've dug up appear to work ok.If these auxillary adapters are anything like the USB video adapters I have used myself, they just flat out don't support 3D acceleration of any kind. SDL 1.3 and DirectX will not help. They will have the same problem as OpenGL does.
I am going to guess that you will have to do software rendering if you want any kind of 3D. (And software rendering at good speeds only works at /very/ low resolutions)
The 7" LCD is a TV set being fed through a VGA->composite device. I was planning on no higher than 800x600. Since there are really no true "3D" elements to the PFD or Nav displays, it shouldn't be a problem to be software-only rendered.
Thanks! g.-- Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind. ScarletDME - The red hot Data Management Environment A Multi-Value database for the masses, not the classes. http://www.scarletdme.org - Get it _today_!