Newbie question on adding RAID capacity

[Philip Prindeville]

I initially did a fairly stock install onto a K8M800 type motherboard
(AMD 64 XP 2800+ processor, 8237R/K8M800 type chipset) with
the SATA raid capability.  I'll soon be adding another drive as soon
as I can receive it (it's one of those Maxtor Diamondmax drives that
have been going like hotcakes).

My question is...  Do I need to do anything in particular to "widen"
the raid stripe and add the drive to the volume?  Will the filesystem
be "re-interleaved" across two drives?  Or do I have to do something
painful like save to DVD, add the new drive, create new filesystems,
and then restore from DVD?

Thanks,

-Philip