Well, my resolution for you is. If your monitor starts to flicker and shakes, then it's time to get a new monitor. CRT monitor tends to do that.
But i don't think it has to do with your grahic card. But again, the moderators are more experience with these things. THEY ARE COMPUTER GEEKS!!(complemently)
I used to have an avitron CRT for like 4 years and now that it starts to do that, i went and bought myself a LCD. Now everything is all good. I don't think LCD will do that shaking thing. good luck mate

