Inspiron 1150 CPU Upgrade

I have so far upgraded the RAM to 2GB on this laptop, and upgraded the CPU once in the past to a Pentium 2.66GHz CPU, and so far it was good.  I recently had I purchase a new battery cause my old one gave the flashing amber light of death.

However, I want to get the CPU even faster than before, and max it out just like I did the RAM.  What is the fastest CPU it can handle?  I tried an SL7NA Pentium 4 3.06GHz CPU cause it had the same 533MHz BUS as my current P4, but got a microcode error, which I felt it would since that is a Prescott core and not a Northwood.

Any information is welcome, thanks.