The worst video 'card' I've ever seen was a SiS chipset integrated video on a 500 Mhz Compaq K6-2 my parents bought. That was marketed at being 'good for games', since it supported AGP, and the amd chip had 3dNow. But it totally sucked!
The graphics performance was horrible! Try playing a simple accelerated game, like Tomb Raider 2 or 3. Barely playable! But the same game in Software mode: Fairly smooth frame rate.
Graphics accelerator? Hell no, that thing was a graphics decelerator.
That summer I got a job (I was a freshman in high school), and bought a voodoo 3, and then my own baby AT Super Socket 7 board, and gutted out the case for my old 486, dropping in the K6. For less than half what my parents paid for a crap computer, I turned old crap into a computer.