a) Backups are your friend!
b) It's a good idea to store data/logs on separate drives (or at least partitions) from your system/applications, then you can just blast the C drive without any major problems.
c) If you use Outlook in Cached Exchange Mode, you can dump all the messages to a .pst file without having access to the mailserver, just in case there are any problems restoring the backup. NB You need to do this before the server comes back online, otherwise you'll resynch with an empty mailbox and lose everything!
d) Roaming profiles don't seem to work if you rename the domain; this led to several weird issues, so I wiped my profile and did a selective restore of bookmarks etc.
On the plus side, this did give me a chance to make some changes that have been pending for a while, even if the timing wasn't ideal. In particular, I've now swapped some hard drives around, completing a cycle that began about 3 years ago:
* Original layout = 4Gb system drive, 75Gb data drive, 800Mb log drive.
* Change 1: replace the IBM "death star" with a Seagate drive of equal size, after the DeskStar crashed horribly.
* Change 2: put in new 20Gb system drive, take out old 4Gb one.
* Change 3: take out 800Mb log drive, replace with 4Gb one (former system drive).
So, this means that I now have the 800Mb drive going spare (Quantum 840 AT, IDE, 3.5"); if any of you would like it, give me a shout. It's hardly going to be worth any money, but it still works fine, and it might be useful as a second drive (e.g. as a staging area before you burn files to a CD). I also have the old DeskStar drive hanging around, since I never got round to applying for a refund, but it's probably too late to claim anything for it now (given that it died in 2002), and I doubt anyone else would have a use for it.
I'm not quite sure what mangled the server last week, but I'm guessing it was the new storage driver (optional patch) rather than any of the critical updates, since I've now re-applied those other patches (and put them on several other servers at work without trouble). That storage driver hasn't reappeared in the list at MS Update, so it may only have been relevant to the 800Mb drive. Anyway, be cautious if you see that one in your list.