Mike Elgan thinks that two laptops are now the minimum required:
Ten years ago, every frequent-flying, executive-platinum mobile professional required a desktop PC back at the office and a laptop for the road. "Ultra-portables" or extreme mini computers were an expensive and optional luxury for serious enthusiasts or big shots with expense accounts. But in the last year, all that has changed.
Three things have happened that have turned around this formula for mobile success:
1. Regular laptops have gotten far cheaper. Moore and his law have brought down the costs of miniaturization, LCD real estate and other components.
3. The Asus Eee PC and its ilk have transformed the market -- and pricing -- for tiny laptops.
This combination of factors has transformed the magic "sweet spot" for what's required and what's optional. The new formula is that an "ultra portable" or tiny laptop is now required, a laptop with the biggest possible screen (within reason) is required, and a desktop PC is now optional.
James Kendrick thinks it takes three:
For the most part I agree with Mike although in my case it's currently a 3 laptop minimum. I don't even own a desktop PC like Mike thinks you need at home, no I'm quite happy with my 17" MacBook Pro with a second monitor attached on my desktop. Throw in the HP 2710p and the Fujitsu P1620 and my 3 laptops are hard to beat. I would disagree with Mike on needing a bigger laptop for working in hotels on trips however. I find the P1620 to be a full-function laptop with no compromises for getting things done but that's likely just me.
Here's an excerpt from the post about screen size and productivity:
Researchers at the University of Utah tested how quickly people performed tasks like editing a document and copying numbers between spreadsheets while using different computer configurations: one with an 18-inch monitor, one with a 24-inch monitor and with two 20-inch monitors. Their finding: People using the 24-inch screen completed the tasks 52% faster than people who used the 18-inch monitor; people who used the two 20-inch monitors were 44% faster than those with the 18-inch ones. There is an upper limit, however: Productivity dropped off again when people used a 26-inch screen.
I'd be curious to see follow-up studies to investigate if it's actually the screen size or pixel resolution is the true source of increased productivity? I'd guess both have an impact, but would expect screen resolution to have a greater impact than screen size. (Excepting micro-sized screens.)
On the other hand, couldn't you get a lot of the productivity gains simply by traveling with a laptop and an AlphaSmart Neo? I still love the idea of a nearly indestructible writing machine with 700 hours of battery life.