Yes that was RAID, and one the type of RAID setup he was talking about was RAID 1 (i think). It is essentially 2 hard drives doing the exact same thing, so if one hard drive blows up or stops working, you can just unhook it and use the other one like nothing happened.
for RAID 1, you need 2 identical hard disks, eg. 2x 7200RPM 8MB cache 250GB Seagate Baracuda's. Once you get 2 exactly identical drives SATA or IDE, you plug both of them in your motherboard or RAID card, enable RAID in your BIOS, and install the RAID drivers from the floppy disk that should have come with your motherboard.
after that, you install windows like normal.
I think thats how it goes, but IMO, unless you need a terabyte of hard disk space, or aboslutly need to keep some sort of super important data from being currupted by a faulty drive, RAID is worthless. Its actually slower than 1 disk if you do RAID 0 and its a waste of effort.