understood... my cpu sux(not a lot tho, but nowadays it will not handle stuff decently even overclocked all d way up) and now i got in my mind that if i still buy that graphics card(agp hd3850 512mb) but in adition i buy a core 2 duo it would really be worth it since i dont wanna throw my older parts to the trash can, i repeat, ofcourse i will buy a kickass sli quad core and stuff apart of this... but i wanna save this to play last gen games (like ut3 for example) with my friends in lan, i dun pretend to make this oldie a kickass system, i just wanna make sure it runs things the best a system that old could.
NOW TO THE GRAIN
now that my mobo is a soc 775 and supports dual cores( biostar p4m800-m7a), i am receiving advice of which could be the best core duo procesor out there in the market for me to buy

and how much could i get it for(new).
aswell as how much could i spect to receive for my current procesor and video card if i pretend to sell em.
once more tyvm u r so supportive guys ty.
EDIT:oh sh*t i have been reading that some older soc775 mobos have compatibility issues with the new core 2 duo, ie:E6600
that has me concerned... will my mobo b able to run it?? and btw i wanna buy the very best core 2 duo processor out there, i am just waiting for your advice to take action and buy it.(oh god i hope my mobo is not a piece of sh*t and support that new processor)