I have been playing with the various methods of overclocking my EeePC CPU, in the process I upgraded to BIOS 703.  However when I tried to revert back to the original 401 BIOS I received the "BIOS to old" error.  With some effort I was able to force the older BIOS.

First a refresher, the Easiest way to update your BIOS.
1)  Format a USB thumb drive using FAT32.
2)  Copy the bios *.rom file to the freshly formatted drive, renaming the file "701.rom".
3)  Plug the drive into a EeePC that is currently off.  Make sure the Eee is on AC power.
4)  Turn on the EeePC, hit Alt-F2 when prompted to enter BIOS (instead of just F2).
Built-in BIOS updater searches for the USB drive, the ROM file, and updates the BIOS.
6)  When prompted to turn the computer off, do so.
7)  Remove the battery, wiat a few seconds, replace the battery, turn Eee back on.
Removing the battery seems to fix some of the battery monitoring issues reported elsewhere.

However the above does not work when trying to install 8804, or 401 AFTER 703 has been installed.  To do this we need to boot from the USB as if it were a floppy, then run an older version of AFUDOS.

** These steps require WinXP/2000.  Does not work on Vista (ok parts do, but not the HP utility)
** If your EeePC is running Xandros/Ubunto/etc use another PC running WinXP to create the thumbdrive

Step 1 - Make Boot Image - You need a .img file for the HP utility
1)  Download Virtual Floppy Drive (VFD)  http://chitchat.at.infoseek.co.jp/vmware/vfd.html
2)  After extracting to your hard drive, browse to the folder and execute vfdwin.exe.
3)  On the Driver tab click "Start"
4)  On Drive0 tab click Open.
5)  Browse to where you would like to save the image, name it with a .img extension.  Select "file" option when prompted.
6)  Click Create to create the image file.
7)  In Windows Explorer you should now see a drive "A" listed.  Right click, select Format, check "Create MS-DOS startup disk".
8)  Back in VFD click Close on Drive0 tab, Stop on driver tab, then close VFD by clicking the X in the title bar.

Step 2 - Make bootable USB Thumb Drive
The HP utility below creates a bootable thumb drive that is the same size as the bootable image created above.  This means that your 4gig thumbdrive will only have 1.4mb (if you used the defaults) available.  When your finished just reformat the thumb drive normally to restore the original size.

** All info on the thumb drive will be lost, backup, backup, etc.
1)  Download HP Drive Key Boot Utility from http://h20000.www2.hp.com/bizsupport/Te … ITY-I23839
2)  Install, execute from Start/Programs/HP...
3)  This is a wizard, Use default options, create a "floppy", browse to the image you created above.  Simple.
4)  OS will loose reference to the thumbdrive once the wizard is completed.  "Safely remove" drive, then reinsert.  (or you acn use drive manager to reassign a letter).

Step 3 - Get files from ASUS
1)  Download the bios update you want, extract to the thumb drive, rename the rom to something easier like "401.rom", "703.rom" etc.
2)  Download an earlier version of AFUDOS at ftp://dlsvr02.asus.com/pub/ASUS/mb/flash/AFUDOS211.zip
3)  You can browse ASUS's support site under "how to upgrade your bios" for more info on AFUDOS.  The version of AFUDOS made available from the official support site prevents the installation of previous BIOS versions.  You must use v2.11 available at the link above.

Step 4 - Update your bios
1) Turn your EeePC off, with AC power plugged in.
2)  Insert your newly bootable drive into your Eee.
3)  Turn on your EeePC, hit Esc key when prompted to enter the BIOS.
4)  This opens a menu where you can select the boot device, select your thumb drive from the list.
5)  If you did everything correctly, your EeePC boots into DOS with that old familiar A\:> prompt.
6)  Enter "afudos /i[yourBiosRomFileHere]".  That's "afudos" followed by a space, then a"/i" then the name of the BIOS rom file you wish to install.
7)  BIOS installs, turn EeePC off, remove battery, replace battery, turn EeePC on.

A note on the bootable thumb drive you created above.  While this one is not really that useful as it only can hold about 1.4mb; you do now have the basis for creating a bootable thumb drive of whatever size you have available.  The boot image you created above contains the all important boot sector, and VFD lets you mount the image.  Search the 'net and you will find numerous tools that create bootable media from a boot image.  mkboot is one such tool, and there are others.