Hello, I recently posted the steps to have ESXi 3.5 u4 installed on an ASUS M2A-VM
ESX 4.0 can also be installed on it but no with the original hardware. At least an additional supported nic is required (ex.: Broadcom BCM5751 ~ $20) otherwise you will receive a non "very intuitive" LVM error message.
1) Install your compatible nic hardware (I suggest a compatible Broadcom or Intel nic)
2) At BIOS change your sata controller mode to AHCI
3) Run ESXi 4.0 install from a CD or USB drive and follow the installation instructions.
4) On the error message "Unable to find a supported device to write the VMware ESX Server image to" hit Alt-F1
5) This will drop you at the console screen. Type "unsupported" and hit enter. No password.
6) run the command vmkload_mod ahci (a small delay is normal)
7) Back at the console type install. Install will start (if you receive an error like "install can't execute", use chmod ), but may still have an error. At the error type Alt-F1 the login, run install, and Alt-f2 to accept.
Now you can see your SATA disks and sucessful install ESXi 4.0
8) With help of other linux installation mount the ESX hardisks and partitions
8.1) Open oem.tgz at root of bootbank partition and include the following file and path on it: /etc/vmware/simple.map
8.2) Add the storage and the nic lines in the simple.map
1002:4380 0000:0000 storage ahci
14e4 1677 0000 0000 network tg3.o
Obs.: The last line will must match your nic hardware. The first line is compatible with your ASUS M2A-VM
9) Boot ESXi
Now you must have ESXi 4.0 running at your Asus M2A-VM 690G SB600 with the onboard SATA controller