Blue and White G3 processor upgrade

Hello, I'm new here!
I love my 300mhz rev 2 B&W G3, so much in fact that I bought another one when a deal came along the other day. The new one is also a rev 2, but has a 400mhz processor and a DVD drive. My question is:
Would it be too hard to transplant the 400mhz processor into my current machine, and keep all of the music and files, or is this the kind of procedure you have to start from scratch with?
If its really delicate I may consider just transitioning into the new machine, but I really don't want to re-install tons of stuff unless I have to. Also is there even much difference in performance between 300 and 400mhz?
(the DVD drive is trivial to move, I'm mainly concerned with the processor/ HD)

Thanks for you help!

I should add that my B&W is running 10.3.9, and that my goal here is to continue running it smoothly and avoid having to re-install.

No, transferring the motherboard (in/on which is the G3 processor) would give you both headache and heartache.

Have you considered a processor upgrade? Using the bits and pieces from either machine, set yourself up with a G3 b/w with (possibly) up to 2 GHz speed. How to do it? PowerMac G4 AGP Processor Upgrades, PowerMac G3 and G4 ZIF Processor Upgrades, Video Cards AGP PCI PCIe for Apple Macs at OtherWorldComputing.com.

The final decision rests on $$$.