Probably the best (IMO) site for visualizing and understanding many of the intricacies of RAID is here. Ultimately, I would almost always run RAID 10, so long as the enclosure and funds allow. You'll obviously have fewer effective bytes available for storage due to the architecture, but the performance is second to RAID 0, with multiple failure tolerance.
Assuming the "drives" to which you're referring are mechanical, you'll most certainly want to spread the I/O load over several, rather than one. Another best practice is to favor RAID 5 over RAID 6 at all costs; the latter's rebuild times are atrocious, as is computational overhead.
Kinda just throwing this out there, but for my money, I would pick up an LSI RAID card (w/BBU if critical). The 9271-8i is a great all-round SAS/SATA card that's available for less than $200 USD.