Are you sure you have a problem to begin with? I haven't done any interesting optimizations in our 3D renderers, and Pirate Poppers didn't have any technical problem with requirements. I use D3D7 and I saw the game running in laptops with onboard videocards with 8 MB of RAM.
About the text issue, can you render to a bitmap and convert it to a texture instead of using GDI every frame? I render TrueType fonts with SDL_TTF which is slow but as long as you don't render every frame and reupload the texture every frame, you should be OK.