replacing old motherboard

I need to replace my old motherboard, but am not sure what my best options would be. My current motherboard is a Intel 845 pentium 4, with a 478 socket 2gb ddr-sdram with 533 mhz fsb. I have 6 pci slots and 1 agp slots I would like to keep it under $150. I am going to use my computer mostly for storing and editing video and audio. I might do some gaming on it. I have recently purchased a new video card and two new memory cards,so I don't want to have to replace them