To setup RAID0 or RAID1, which is what your board supports, you will need two (2) HDDs. You can still setup one HDD on the SATA Controller on your MoBo to allow future use of all you IDE Controllers for optical drives or a backup HDD.
Will there be a benefit? That depends if the SATA BIOS you have & the current SATA Drivers are better than the IDE Controller & Drivers available. You will have an added screen during bootup, SATA RAID BIOS(will show up even if not being used as a RAID Array simply because you are suing the controller), & identify the drive conected to your SATA Controller. This will add a few seconds during bootup.