raid

What information do you require, not much point in writing a long reply outlining the various forms of RAID and their good and bad bits if:-

A) You've already read about it
b) Don't say what you're goals are (eg speed, data security or both)

RAID can offer faster speed than any single drive solution, data security by mirroring two or more drives so they are identical in case one fails, or something in between which gives better performance AND data security, but for this last option you would need a motherboard or controller card that supports this level of RAID along with at least 3 preferably identical drives.

Probably best if you stated the amount of money you'd like to spend, what motherboard you already have and what you would like to achieve before someone rattles off the benefits of having 4 15l SCSI Ultra320 drives on a PCI-X controller card in RAID 5 configuration.