Imagine realtime hardware accelerated HD previews... with compositing, 3d effects, color correction...
Okay well I'd settle for a little faster preview frame rate when you load up Vegas with effects. Vegas seems to be very single-threaded when it comes to effects... and since processors these days are not getting all that much faster when it comes to single-threading, I think the GPU is the only solution! I know Adobe's got this working in PP but I'd much rather stick with the Vegas UI if there was just some way to get around that processing bottleneck...