that gpu is old as dirt
don't buy such gpu, driver support and lack of directx support are a problem with those gpus
what is the rest of the specs of that pc?
to answer your question that mx920 is weak when compared to that old weak gpu, perhaps the double of the capacity in terms of frames per second
if you plan to use the gpu on the desktop for games, amd or nvidia are options
if you plan to use it to video edition with tools like adobe premier or after effects, nvidia will perform better
what is your budget for this new cpu?