For a long time moving SQL servers underneath Enterprise Vault took a bit of time and a bit of planning. Actually plenty of time and plenty of planning!
I spotted something rather interesting on the Enterprise Vault RSS Feed the other day:
EV SQL Move Tool
http://www.symantec.com/business/support//index?page=content&id=TECH214373
I haven't personally tested it (yet) but well, yeah.. wickedly good, right?