worthit to replace a banias 1.4 to a dothan 2.0 procecssor?

Hello,

Is it worthit to invest into a processor? Would there be a significant increase or a noticable performance increase if I would upgrade the processor of my laptop from a banias 1.4ghz 1mb cache to a dothan 2.0ghz with a 2mb cache.

my notebook is a dell d600. A new notebook would cost around $1000, a new processor would cost around $300.

I've read in the articles that the lcd can be replaced, is there also a website that sells motherboards that can replace older boards of notebooks so that it could support new processors, memory, video chip?

Thanks