Follow the instructions in "Preparing to Work Inside the Computer."
Remove the left, right, and center hinge covers.
Remove the keyboard.
Remove the display assembly.
Remove the keyboard bracket.
Remove the video card.
Loosen in consecutive order the four captive screws, labeled "1" through "4," that secure the microprocessor thermal-cooling assembly to the system board.
Lift up the microprocessor thermal-cooling assembly and remove it from the system board.
Doesn't look too hard. Don't know about warranty's, should be fine as long as you don't break anything in there.
Not sure where to get the higher speed p4 mobiles, but found this intel spec sheet with the OEM order number on it.
Mobile Intel® Pentium® 4 Processors Return to list
sSpec Number SL77R
Processor Frequency 3.20 GHz
CPUID String 0F29
478 pin PPGA Core Voltage
533 MHz Thermal Guideline
D1 Thermal Spec
L2 Cache Size
512 KB Manufacturing Technology
L2 Cache Speed
3.20 GHz Bus/Core Ratio
Product Order Codes
OEM Order Code
This processor includes Hyper-Threading Technology.
This processor includes enhanced Intel SpeedStep® Technology.