If you need that acceleration I think it will come down to a choice between that and the software that requires 2.4.x. Are there no alternative apps?
AFAIK the only alternatives, with the exception of maybe a few embedded video chips like for some laptops (and even those are still all framebuffer drivers, not accelerated), for nVidia cards are nv, nouveau, and nvidia (proprietary). The only other possibility, perhaps, is replace the video card with one on which the proprietary driver will build...... a lot of work for one old app