Glad you got sorted Spanners.
Mip Mapping is a must for turning off. The rest I have found is a question of choice, and circumstances.
Here's what I do. I get whatever it is running, say FS2K or some other graphic intensive job, try and use pause - then you can alter what you want, try it, repeat and so on. Very problematical I'm fraid to say.
It does work if the programme will 'allow' it though.
The best place to see what others think is forums - these have those you have been there, done that and know what is what. So try your manufacturer and see if they have a forum. They usually do.
BTW don't forget to download DIRECTX7a. DON't be mislead by anyone. It's a must and works OK. Directx8 is due out anytime now.
Best o' luck.