I have an IBM Thinkpad X40 that I first acquired in 2005 (but I believe it was actually sold to my employer in 2004). I used it at the bedside as a visiting hospice nurse, then when these machines were retired, I bought a few for myself from my employer because I like the physical design of the machine so much.
It has no internal removable disk drives, no floppy, no CD. These are housed in a removable docking base. It is the design grandfather of the current ultrabook (think MacBook Air) concept.
My MacBook Air (fall 2011 model) is lighter and thinner, but it is so because of hardware and technology that did not exist in 2004. The design concept is the same--clamshell, computer guts topped with keyboard on the bottom, a maxed-out edge-to-edge LCD for a lid. I also still like the X40's red nipple joystick (between G, H and above B on the keyboard) for mouse emulation, no trackpad.
I think the X40 (and X41) was the finest expression of the design concept by IBM. The X60 was too thick, heavy and hot, trackpads got in the way and added too much weight and space, and it just got worse from there. By the time I had another ThinkPad (Lenovo had taken over the business from IBM and) it was an X200 tablet, and that thing was a behemoth by comparison.
The X40 was made obsolete by a combination of the motherboard maxing-out at 1.5 GB of RAM and Windows XP bloating to the point where 1.5 GB just wasn't enough RAM to yield an acceptable user experience. I began installing Debian Linux on these machines in 2006 and they've since remained plenty fast to provide a mobile desktop even while staying current on the latest stable release of Debian (currently Wheezy, version 7.6).
Lately, the problem had been the disk drives in these machines. They were old and slow. Also, the batteries only last about 3 years, so I am on my third generation now. Luckily, there's enough of these machines in use that they still make new batteries.
I replaced the old hard disk in my X40 with an solid state disk and the difference in performance is remarkable. With the SSD, running Debian Linux 7.6 with the lightweight XCFE GUI environment, this machine rocks. It is fast, light, cool, and I get almost six hours of use from one battery recharge. The SSD draws much less power.
I feel like the x40 is kind of like the VW bus of laptops, something that future collectors will covet for actual use. Overlooked in it's day, people who understand the vision in it's design will appreciate it's timeless simplicity and practicality.
It is likely that if you put a slimmed-down, low resource intensive, installation of XP on this machine with an SSD it would do okay, except that XP would trash the drive because it isn't SSD aware.
I think both Apple and Microsoft are floundering a bit with where to go "next" with laptops. Microsoft is pushing this laptop-tablet hybrid, and Apple is pushing the Air lighter, thinner and more powerful, but not much else. I wonder if they fear that a detachable keyboard on the Air would adversely influence iPad sales?
Consider the notion that there's no where to go. The X40 concept is as good as we can get while we are primarily relying upon a keyboard and mouse to interact with the machine.
Much in the same way, no one every really improved on the family mini-van concept after the VW Bus, they may be better expressions of the concept than that top-heavy tin-can on wheels that was the VW model in the 1960's, but the idea is the same. One might argue that SUV's are an improvement, but this is much more like the detachable keyboard being an improvement. It is still just an extension of the basic original idea.
Some designs are complete expressions. A fork is a fork. A bow and arrow is a bow and arrow, there's not a "better" way to do that, just more technologically advanced.
So, I'm happy with my souped-up X40, and I like the fact that the computer I most use for writing is an old relic, like an old IBM selectric typewriter. It takes a licking and keeps on ticking. There's something reassuring about the fact that personal computers have matured to this stage. We know what works. That's a good thing.