I currently have an inspiron 9400 laptop with a T2600 2.16 ghz processor socket 478. What would be the best processor to replace this one?
The three fastest are the T7200, T7400 and T7600, though the last of these is expensive. None are made any longer but may still be available as old-stock or used.
You CANNOT use any of the newer Socket P CPUs - i.e., the T7x00 with x= above 6 or odd, or any of the P or X CPUs.