Wow, lots of serious comments on this one, I have for one built more than a few Pci builds since AGP, but thats what I do for a living, AGP is not dead, and more than half of the upgrades I do for customers are still running Agp boards!
Bear in mind these kinds of users do not encode huge HD files, nor render 3D or run web servers on their home machines, they surf the net, listen to music and make a few documents, look at their photos they have snapped with their digital cameras and possibly game a few light titles.
They do not care about running the latest and greatest Graphics card and probably wouldnt be able to tell the diference between the advanced settings in most modern games or even be able to find the advanced tab to change them , and even more they wouldnt care less to be fair!
So as such, yes running a 4650 on Agp system will have its issues and will cost more than the current Pci cards, but for someone not at the edge of cutting technology who just wants to play some newer games once in a while without replacing the rest of the PC because they dont buy into throwing away working machines then yes, If they will pay I will install them by the dozen.
Business is business, thats the reality of it, so go Gigabyte.
Ps, my second system is still P4 3.0Ghz @ 3.7 and 1950 Pro and it still rocks and even plays crysis at med settings 1280x1024 smoothly (ave 30fps) and rips any MMorg apart with ease (Its main use)