That is a significant speed bump Steve, 40% bump in speed with a 20% increase in processing power, if I did the math right!
I find that in some instances my eMac is faster than my iBook though the iBook has a faster processor. I never looked into why, though I took notice of that fact from the start.
I'm up in the air on shiny screens, I use a Toshiba notebook with one and sometimes it has it's advantages, in brighter light, but I can't say it's a total improvement.
iMoved the thread, though I guess it could go either way, but since it was Mac specific, hardware, purchase, comparative analysis, I made a judgment call.
Good luck at eBay!