I have a feeling its not, can someone explain why?
why not just get p5kpl-am or gd41ty board? that p5vdc-mx is based on via p4m900 chipset which is aged and not support many modern hardware like pcie 2.0, 65, 45nm processor and other device. and e8400 is 1333fsb while it support 800mhz which your e8400 will be hugely bottleneck if installed(but i doubt it will ever runs on that board.) so get other board if you want to buy it or sell it if you had one. it's old and not compatible.