Best CPU upgrade for an inspiron 530?

Manufacturer: Dell

Dell Part Numbers: RY007 0RY007 CN-0RY007 G679R 0G679R CN-0G679R RN474 0RN474 CN-0RN474 K216C 0K216C CN-0K216C GN723 0GN723 CN-0GN723

Model Number: G33M02

The G33M02, that supports up to Core 2 Duo processors

Intel Core 2 Duo E4300 (1.8 GHz, 800 MHz FSB)
Intel Core 2 Duo E4400 (2.0 GHz, 800 MHz FSB)
Intel Core 2 Duo E6320 (1.86 GHz, 1066 MHz FSB)
Intel Core 2 Duo E6420 (2.13 GHz, 1066 MHz FSB)
Intel Core 2 Duo E6550 (2.33 GHz, 1333 MHz FSB)
Intel Core 2 Duo E6750 (2.66 GHz, 1333 MHz FSB)
Intel Core 2 Duo E7300 (2.66 GHz, 1066 MHz FSB)
Intel Core 2 Duo E7400 (2.80 GHz, 1066 MHz FSB)
Wolfdale Core 2 Duo, E8400, 3.0GHz, 6MB, 1333FSB, 65W, E0
Wolfdale Core 2 Duo, E8500, 3.16GHz, 6MB, 1333FSB, 65W, C0
Wolfdale Core 2 Duo  E8500 (3.16 GHz, 1333 MHz FSB)
Wolfdale Dual Core Kit, E8600, 3.33GHz, 6MB, 1333FSB, 65W, E0