I am going to make a few suggestions only as I have not yet messed with Vista, I'd not be able to give you definite answers but remember:

~ If you have any critical data, program files, settings, etc. worth backing up, then do so before you do anything!

~ If at all possible (if you have a 3rd party partitioning software and adequate space on your HDs), try to re-partition your existing setup if you do not want to lose the current installation of XP (I sensed that you already have an installation of XP on this system, if I am wrong disregard this). After re-partitioning the RAID-0 system and creating enough space for Vista installation,

~ Run the Vista compatibility check on the new system, which should warn you of all potential issues that it will detect (fFrom what I heard, Vista is pretty good with this particular procedure).

~ If all checks out fine, check for Vista drivers on the net for all the hardware currently installed on the subject system prior to running the installation.

~ I recommend saving the downloaded drivers on a CD or USB Flash disk in case the local disk becomes unaccessible due to whatever reasons.

Hopefully one of the knowledgeable fellas who have the related experience about your other concerns will chime in...

Good luck,

~TL