My experience with software RAID1 under Ubuntu was rather good. I did a
RAID install with two IDE drives for the first time about two weeks ago
which was surprisingly easy. And I've had a play with raid5 on three
scsi drives.

Also rebuilt a server last week.. two 200G SCSI drives, both partitioned
as 198G raid and 2G swap, then configured the two raid partitions into
one /dev/md0, then went back and set up /dev/md0 as ext3 root.

Only one thing to watch out for, if the drives were already partitioned
for RAID the installer gets horribly confused. Remove all
previous partitions from all the drives and reboot so the installer
kernel doesn't have any 'preconceptions' about how the drives are
configured, and everything should be fairly straightforward after that.