OK I'm getting somewhere.....
I went into the SCSI utility (CTRL-A) and disabled HostRaid.
Rebooted and ta-da Vista could see my drives, only I couldn't select the drive I wanted because it was an 'Extended' drive not the 'Primary' - obviously XP is the primary drive.
So I re-booted to go into XP to check out what I had on the 'Extended' drive before I switched the drives over in the BIOS as I can't partition drive 0 as there isn't enough space on it!
And guess what XP BSD'd on me, I tried to do a repair install of XP but the F6 additional drivers section BSD'd when installing, because the drivers are for HostRaid enabled - AGGHHHH.
So it would seem that XP will run fine with HostRaid enabled even if there is no raid array running, yet Vista will not, I don't know if it's a driver issue or a Vista issue, either way I'm screwed.
So I've had to re-enable HostRaid on the SCSI card to get XP to boot so I can go get the non-HostRaid drivers from the Adaptec website.
I will then have to disable HostRaid, do a repair install of XP using the non-HostRaid drivers, then check everything is OK.
If all is OK I will then have to switch primary drives in the BIOS so I can then start the Vista install.
What a palaver

, I'm then not sure if I will be able to dual boot as XP certianly won't boot with that drive not being 'Primary' and I will have to wait and see if once Vista is installed on the other drive whether it will boot if I switch it to being the 'Extended' drive in the BIOS.
Does anyone know of this Vista 'multi-boot' program will help with this situation as it will be a nightmare if I have to keep going into the BIOS to swap drives each time I want to change the OS I want to boot into.
Oh well I guess at least I've made progress if nothing else!
Regards, 1DMF