The bottom line is that AGP cannot compete with PCI-E GPUs, the bandwidth that PCI-E can handle alone is far more than AGP.
The MOBO you have acquired has onboard GPU and if I am honest should only be used for a low end PC, browsing the web, etc.
Dont waste your money on older technology unless its for a specific purpose, the hardware you have got in your current system will outweigh the recently acquired, if needs be replace the 9500GT with something more powerful or add a second 9500GT for SLI
I know its not what you want to hear, but its honest :)