Not sure if this has been discussed here or not but I didn't see another thread after a search so here goes:
There is a new video overlay/enhancement system that came out a few months back called SweetFX. I am currently using it with DCS World but it might give Doomsday a boost as well. All it does is take the current rendered image and tag on some after-effects like gaussian blur/film grain but the resulting images make games look a lot better and less computer like.
http://www.guru3d.com/files_details/swe ... nload.html
There is a 64bit version as well. I'm going to give this a shot later this evening when I have time but I thought I would drop a post first.