|Taken directly from the ASUS manual page A-13.|
"Using the Recovery Partition:
1.Press [F9] during bootup.
2.Press [Enter] to select Windows Setup [EMS Enabled].
3.Select the language you want to recover and click Next.
4.Read the ASUS Preload Wizard messages and click Next.
5.Select a partition option and click Next.
Recover Windows to first partition only.
This option deletes only the first partition and allows you to keep other
partitions, and to create a new system partition as drive "C".
Recover Windows to entire HD.
This option deletes all partitions from your hard disk drive and creates
a new system partition as drive "C"."
If the proper F9 menu options aren't available, it's possible the Recovery Partition was somehow deleted. Did you confirm that the partition exists?