I've had some problems in the past when installing Vista 64 when the destination hard drives (raid) could not be used for the install because it (the raid) was not the primary boot device. Try changing your boot order to put the raid first, the your dvd-rom second. When no OS is detected on your Raid then it should jump to the Vista install dvd. Give it a try and let us know!
I got it working, although not exactly as I was hoping.
I did the following and I am not sure if one thing or many contributed to a successful install:
In Vista Install, shift F10 to get to command prompt. then I ran diskpart and cleaned the the RAID mount. It took most of the night. all 4 hardrives were previously used and desipte deleting all the partitions on them, I thought there may be some linguring boot records.
I also connected an old 200gb Sata as I had almost given up on vista on RAID.
Then the install took, but it did put the boot recods on the 200gb drive.
I am not sure but I hope I can move those boot records at a later date as I really don't want to be using that 200gb drive in this system.