That PCI card will not work (the AGP 2mx card can be flashed to work in both mac and PC but you only have PCI in that 7600).
The 3dfx Voodoo 3 card an be flashed to work in the Mac and it is way faster than the motherboard video. (described at www.xlr8yourmac.com
) I know that the Voodoo cards have been sold at computer fairs for 5 dollars or so.
has both ATI 128 (fast 2D and 3D) and the TwinTurbo (fast 2D but no 3d).
The new ATI 7000 card is more expensive at 100-120 dollars and really not much faster than the AT128 but it offers support for two monitors.
With a 100 MHz CPU the 2D graphics is CPU limited and fast card will not help, alredy with a 200 MHz CPU the motherboard graphics is a limitation and a PCI card will help and with 450 MHz G3 it is a huge limitation in subjective speed of the computer.
I would most definitvely get a card either the ATI 128 or the ATI 7000, scrolling in word, web pages and opening windows in the finder everything will feel faster. A optical USB mouse will be nice as well, now the nobrand ones are wery cheap