I think you've been given out of date advice. If you try to install Windows XP or Vista on the 6gb ports it will not detect the controller. Windows 7 should detect and install on the Marvell controller just fine.
Go into the BIOS settings, ensure AHCI mode is set (refer to the manual for what setting this is), then proceed to install Windows.
After windows has installed, you will have the generic Microsoft AHCI controller driver installed for all of your SATA controllers.
Asus will have bundled a drivers CD with your motherboard, but I prefer to get the latest drivers online rather than use OEM driver CDs, which are usually a few versions out of date.
To make full use of your SATA controllers, you'll need to upgrade from the default MS drivers.
For the Intel 3Gb ports, there's the "Intel Rapid Storage Technology" 10.1.0.1018 driver, available here:
http://www.intel.com/p/en_US/support/highlights/chpsts/imsm (Latest downloads)
And for the Marvell 6Gb ports, there's the "RAID: Marvell 6Gb Driver" version 1.2.0.7103 available here:
http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=19551&ProdId=3273&lang=eng
You should be able to install both of those drivers without any issues after you boot to windows for the first time.