In my EeePC Software User's Manual, on pages 3-4 to 3-6, there are instructions for restoring the Linux operating system image from a USB Flash Disk. This method uses a Windows PC to load the image from the ASUS EeePC Support CD to the USB Flash Drive, then boots the EeePC from the USB Flash Drive.
It says, "9. Restart the system and press <ESC> on bootup and the Please select boot device screen appears. Select USB:XXXXXX (may be labeled as the USB flash brand name) to boot from the USB flash disk drive." I pressed ESC on bootup and the Please Select Boot Device screen did appear.
On my ASUS EeePC 1000 netbook computer, pressing F2 promptly on bootup brings up the "BIOS Setup Utility", "v02.58 (C) Copyright 1985-2004, American Megatrends, Inc." Tabs across top of screen are: Main, Advanced, Security, Boot, Exit.
Selecting the Boot tab brings up a Boot Settings list:
Boot Device Priority
Hard Disk Drives
Boot Settings Configuration
OnBoard LAN Boot ROM [Disabled]
Boot Booster [Disabled]
Selecting Boot Device Priority brings up a Boot Device Priority list:
1st Boot Device [Removable Dev.]
2nd Boot Device [HDD:SM-ASUS-PHISON]
3rd Boot Device [ATAPI CD-ROM]
"Specifies the boot sequence from the available devices. A device enclosed in parenthesis has been disabled in the corresponding type menu."
Of course, there is no HDD or CD-ROM available on my EeePC. I think HDD:SM-ASUS-PHISON is the Solid State Drive used in lieu of a hard disc drive. And apparently  are parentheses. You can rotate the three choices using + or -.