I pre-cleared my 2 x 2TB drives.  I moved some data onto one of them after formatting with ReiserFS.  I kept other one unformatted, as I would use it for my parity drive.  After I got a bunch of data on the formatted drive, I decided to create the array.  I assigned the Hitachi as the parity, and the WD20EARS as disk1, but it said there was no data drive when I went to start the array.  Does the drive really need to be zeroed to be added as a data drive, or can I add a drive with data on it to the array?

Did unRaid make the reiserFS on the drive? UnRAID will only recognize reiserFS if it created them itself. The reverse is not true, i.e., other systems will recognize the unRaid created reiserFS normally. Where did you create the reiserFS?

I created it after I did the pre-clear, so yes, with unRAID.  I did a reboot of the machine, and it appears to like the data drive as disk1 now

 

Now to do a pre-clear on the 2 x 1TBs...and get those in the array also.