Yes, the trident and the Monster 3d2 can be hooked together. The Monster 3d2 comes with a cable that runs between your existing 2d/3d card and the Monster card.
I have a trident (4mb) 2d/3d and a Monster 3d2 running on my K6-2 300 OC'ed with 64 RAM. It runs good. I get about 60 fps in 800x600 in Quake2 timedemo1.
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