ive never set up raid drives, i think its 3 drives you use, 2 to hold the info in 2 parts and the other holds the info to stick the 2 parts back together....if one fails you can restore any part....not 100% sure tho.If you are going for business storage, you may want to consider a RAID setup for the hard drives. I cant remember if it is RAID 0 or 1 etc but...
It uses two drives and stores info on both drives. If one drive fails, you only have to replace that and you get all of your info back. Rather than, one drive with all your info, or one extra, backup drive.
Good RAM is really cheap now as well, due to DDR3 being about, you can get very high quality DDR2 on the cheap.
Let Jahlad build you one.
FYI: 3 processors isn't an option. hehe