Removing VBPro will not harm/damage your XP or Vista system; VBPro is simply a better way for users to manage their Vista boot entries, but is not physically part of the BCD. Also, I'm not sure if I understand here, but changing OS entries in VBPro does not affect the boot.ini for XP If you want to change the name of an entry in boot.ini, you will need to open the file and edit it.
Just out of curiousity, does Vista recognize your RAID XP OS in disk management or Explorer (While your're in Vista I mean)? That's an interesting setup; hopefully some of our RAID folks will take a look at this and see something for you to try.
One last thing before I hit the sack....... regarding the drive letter assignments; Vista will try to make itself the C: drive in most instances in dual boots, and even multi boot environments. HOWEVER, this does not physically change the partitions, only how Vista sees them. At one point, I had 4 different Vista builds installed and no matter which one I booted to, it called itself C: The important thing to remember on the dual/multi boots is to avoid changing drive letter assignments unless you are in your "System drive" OS (Most people this will be XP) and ensure you use the drive letters as Explorer sees them.






... but I wouldn't advise it nor attempt it on a client's rig

