I say go with VGA. In fact, you have to go with VGA. You do not have a choice.
VGA or AGP is not a choice. You know there's red and green applies right? You question here is the same as asking, "Do I get red, or do I get apples?"
VGA = Video Graphics Array All cards are vga.
AGP = Accelerated Graphics Port This is a type of connection between the graphics card and the motherboard. If the motherboard has an AGP type slot (which I'm certain it does) then you need an AGP video card.
So your card will be both AGP and VGA.