If that program gives you AGP information, then an AGP card is the one you want. Which is what you picked out. If you want a low end card, a Geforce 5500 or Radeon 9800 pro would be the better option for games. Even they are being stretched by games such as Half-Life 2, so that would be the minimum I would get.
If you had a manual for your motherboard, or if you knew the model and manufacturer of it, this would make it easier to find whether you have support for AGP.