Ray
I got the second 500gb drive and installed it (waited for a full resync and then rebooted) and then did the steps here:
http://wiki.contribs.org/Raid (I see they have changed substantially since I last attempted)
It seemed to work ok and a df -h command showed 456gb but I couldn't map it with my XP box - it just showed no drives on my server in explorer.
I rebooted everything and I still can't see it with explorer even though I could access the console from the xp box no problem.
Disk redundancy now says:
Only some of the RAID devices devices are clean
Manual intervention may be required.
It looks like md2 is "resync = 30.7%" and its going to take
344 min !I have the data backed up (and that only took 120 min) so I am just going to start over again with a fresh install on the 2 - 500gb drives.
Just wanted to let you know how it turned out.