Thanks for your helpful and comprehensive comments.
You have highlighted precisely why I remain puzzled why I am having problems and why I have not dismissed completely using Mandrake under this card. Some key points are:
1) the install process (as far as it gets) recognises the RAID 1 array (2 x 60GB drives) as a singe drive and partitions root, home, usr, swap as ATARAID/hde etc
2) It formats the partitions without error - though I say this with caution because format to ext3 reverts to ext2 when I reboot
3) The install process stumbles when it appears to access the Swap partition
4) If I use the autoallocate option on the unpartitioned area of the RAID array it does not create a swap partition. Hence my focus on the swap partition as an issue.
I am looking for guidance on whether the logs will give me a clue but being a newbie I am not sure how to go about this. The install process doesn't seem to give much option here except "expert" mode (which I am already using)
Your idea of using one of the CD live distro is a good one, I will try this The fact that I can interact at the ATARAID level during install implies to me that the drive is being recognised as a valid drive so I wonder if this action may be inconclusive.....
Chris