There's also other things to take into consideration too, Fish, like soundmegs and zonemegs. Soundmegs are self-explanitory, but zonemegs are related to the textures in maps and therefore have to be taken into consideration when running a server.
Try these settings:
seta com_hunkmegs "512"
seta com_soundmegs "192"
seta com_zonemegs "128"
Please also make sure, in compatibility mode, that you run the game as Administrator.