Right with you there, paparazi, it's the minimal framerate that counts, not the fancy DX9 extensions.
That said, I'd skip on the 8X part. AGP 4X was a tremendous benefit over AGP 2X, which was quite a boost over regular AGP, but AGP 8X is but a name and brings no perceptible additional performance for the moment. The new standard that is coming is PCI Express, and that will blow any AGP out of the water. PCI Express is for this year, so I'd forget AGP 8X, it will go nowhere in time to be useful.
You might be more interested in getting a 4X TI4400, which is more powerful than the 4200 and just might be less expensive since it does not have the useless 8X moniker which is more marketing than anything else.
Pascal.