You can disable it in the BIOS for now, as you don't have a SerialATA drive. SATA is the successor to parallel ATA (the 40-pin IDE cables are parallel ATA). It allows faster speeds, but currently is only available via an addin controller (or chip added to the motherboard), and there aren't any drives available yet. Disabling it will avoid loading drivers for an unused piece of hardware.
You can easily find more information about SerialATA on AT and many other sites. It is the future. 🙂