takmadeus, where are those screenshots you've promised to show up?
Screenshots are located in your SupraHLE folder : 01.tga, 02.tga and so on.
You can easily convert them to jpg or gif.
However, even tho' evoodoo is in my opinon the best wrapper ever (biased opinion since latest versions are SupraHLE optimized), I doubt that it is the most accurate for your gfx configuration.
Read : not the fastest.
However, try enabling some video options with evoodoo. The one after the other, and see if it improves gfx quality or not.
I can't provide you with many more advices since SIS emu users remain rare.