I wrote an article for PC Week in 1990 about the new Intel 386 SL chip. This was the first chip made specifically for laptop computers. And everything changed. I suspect the Intel Atom chip will change everything again.
For 19 years I have never believed a laptop would be a "desktop replacement". For me the ergonomics and price factors have always favored a desktop for prolong work. Which is why people plug in full size screens and keyboards into their notebooks. But they pay a hefty premium.
When I travel, small and light is good. But I still need to see what I'm doing and I would like to run "real" applications. The new crop of 10" netbooks with nine hour battery life does the trick. But for real work, I like to use a desktop. Ergonomically and budget wise, it just makes sense. So rather than dropping $2K on a powerful enough notebook (plus screen and keyboard) you can spend $1K and get a great netbook and a Mac Mini. I like the mini because 1) it's very quiet and small and 2) it's OSX. The netbook is XP, but since I run the same application on both platforms, that's o.k.
The key to making this work is Dropbox. All my current project files are stored in Dropbox, and automatically synched on both machines (plus stored on Amazon S3 for safe keeping).
And since I have a netbook, I can use a very small flip phone that fits in the change pocket of my jeans. Since all my email is forwarded to Gmail, I can read and write from any email address. I admit I'm not as good using T9 as some people, but it works for me.
And as a bonus, the netbook fits in a standard file folder. Very nice going into meetings. And here's a secret, you can upgrade those netbooks to 2gb memory for $30 or so.
So it is possible to have it all and not go broke. (and yes, that Compaq was my original portable computer)