But I get the point, just ship the devices with a larger Flash ROM chip;
Large enough for the end-user or reseller to flash the OS of choice into it.
The ROM devices exist today, they just aren't being soldered onto the m.b.

Why? Because of slow device read speeds. But you might be able to do
this in twice your goal (5 to 6 seconds).

To get a better feel for this, check out: openWRT.org -
Which started out life as a project to put a full OS on appliance devices.
(At least ones with enough Flash and RAM included on them.)

Note that we have already seen mentioned here NetBooks that are shipping
with systems based on Kamikaze 8.x

So there are systems now that are close (closer for the hacker) to your vision.
If Gdium would change that USB key slot to CF card. . .

But I get the point, just ship the devices with a larger Flash ROM chip;
Large enough for the end-user or reseller to flash the OS of choice into it.
The ROM devices exist today, they just aren't being soldered onto the m.b.

Why? Because of slow device read speeds. But you might be able to do
this in twice your goal (5 to 6 seconds).

To get a better feel for this, check out: openWRT.org -
Which started out life as a project to put a full OS on appliance devices.
(At least ones with enough Flash and RAM included on them.)

Note that we have already seen mentioned here NetBooks that are shipping
with systems based on Kamikaze 8.x

So there are systems now that are close (closer for the hacker) to your vision.
If Gdium would change that USB key slot to CF card. . .

What about OS in rom (ok so CE and even older RISC OS) used to do this…

Has a lot of advantages (lower boot time, resistance to virus taking out the OS etc. etc.)

ROM is cheap these days so why havn't we seen things move to this setup except in embeded devices. Add a quick booting Bios specifically designed for OS in ROM and the OS it'self and I am willing to bet we could have full OS booting to desktop in 2 or 3 seconds.

John