The spectra 2500 is an excellent choice, but it is the most money of all the riva tnt chipset video cards.
If you want fast performance and want to spend the least amount of money, consider a different AGP card based on the tnt chipset, such as the Creative Riva TnT or the Velocity 4400.
Just make sure you get a tnt card, it is the best AGP 2d/3d chipset currently available, and any of the cards based on it would be a good choice.