Fastest CPU a D630 can handle?

I was wondering what is the fastest cpu that a Dell Latitude D630 can handle?

Will I notice a difference from what I have now?( currently has a T7250 Core Duo 2Ghz with 4gb of ram)

If you can please list the model number of the cpu for me to look up to see if it is worth the effort.

I see there are other posts online but nothing recent. I have no idea where the A19 BIOS update was located as I only see A17 on the Dell site for available downloads for this model.

www.tomshardware.com/.../dell-latitude-d630-performance-upgrade.html