If i got a video card with an agp 8x interface, but my computer only had an agp 4x interface, would it work?

I want to get a new video card for my computer, its an older computer, i'm not sure how fast my agp interface is, so how can i figure that out, and will a card that runs on an 8x interface work on a computer that only has a 4x or 2x interface?|||It appears that the question period has expired. If you have received an answer that meets your needs, please choose a 'best answer.'

Regards.|||I cant say for every card without testing, but I know that a GeForce FX5200, which is an 8x card, DOES work on a 4x slot.