The Q9450 uses a LGA775 socket, while the X3440 uses a LGA1156 socket. You would need a new motherboard.
Look for an i7-880 instead. It's faster than the Q9450 (singe-core and multi-core), and uses the same LGA1156 socket as the X3440.
Look for an i7-880 instead. It's faster than the Q9450 (singe-core and multi-core), and uses the same LGA1156 socket as the X3440.

