I can't say for sure if that motherboard will support a newer type cpu.There are bios updates,but i can't again say that these make that support happen.Maybe ask on that HP site you started a similar topic.
For the bios updates,
http://h20564.www2.hp.com/hpsc/swd/public/readIndex?sp4ts.oid=5160082&swLangOid=8&swEnvOid=4058
i think this is your pc but check for yourself too,again maybe get a second opinion on that HP site.
You could see if there would be a i7 2600 for sale,maybe even second hand for a decent price which should be supported according to that site you linked.This on it's own should give a performance boost looking at the speed differences which is 900mhz on all four cores stock.
A small,but better cooler like the hyper tx3 or similar,because they are better,would make it imo for such a cpu easier to use the turbo speeds.