SATA port shortage

I have a new build with an Asus M4N82 Deluxe mobo (Windows 7 64bit OS).
This board has 5 internal SATA ports (with #5 port being AHCI) and one external port.
When RAID is enabled in the BIOS, the manuel says on-board ports 1-4 are by default RAID only.
Right now the RC OS is installed on a single 500GB SATA drive,
but my future plans are to install 3 SATA hard drives in RAID 5 mode, which only leaves one port
for optical drives.

My question is this...
Has anyone used an add-on PCIe card for running SATA optical drives only?
I realize that the CD, DVD or BlueRay drives installed on such a controller would not be bootable,
but this fact does not concern me at this time.
If the answer is yes, do you have a recommendation for a card that would work for Windows 7?

Thanks in advance for your time

Thanks for the advice.
That sounds like a good solution for me.
Does this model card run on Windows 7?

Check a little more closely about ability to boot from a drive connected via a PCI bus controller card. In some cases it can be done. You need a controller card that can hook its BIOS chip into the mobo bios system, and you need a mobo BIOS set up to do this properly. Start with your mobo maker's (ASUS) docs and tech support guys to see if it;s possible from that end, since you can't really change that. If the answer is yes, ask specifically whether they KNOW of PCI or PCIe SATA controller cards that work well for this purpose with your mobo.

Also check with the makers of candidate SATA controller cards. They know more about this, and may have specific info on compatibility with your mobo.