Your windows copy may only work with an hp bios board. I tried changing to a non-hp board, and microsoft wouldn't activate windows. Use cpuid to id your cpu and memory. Then do a search for the specs to see the maximum memory amount it can hold. Cpus are a little tricky to figure out with oem boards, but your current board only works with old p4's. If you decide to change the board, I recommend my old "boston" hp model. You can get one from ebay for $60 plus $25 shipping. Your old ddr2 should work with this board, and it will run with the e7200 or e8400. Not sure about quads. So you're looking at around $200 to upgrade using your old windows copy.