[see update about the two "versions" of WDS and a later update as the saga continued ...]
Now, it must be admitted that if my Dell XP laptop were sentient I'd be condemned as a cruel master. I torture the darned thing. I know few who see as much of XP and Office's brittle nastiness as I. Maybe if I treated OS X the way I do XP it would break to. (Vista? You're joking, right?)
That said, a recent flurry of cascading messes taught me a new lesson and reminded me of old ones.
- Sometime in the past few weeks my 75GB drive suddenly had only 9GB free. It's dangerous to fall below 20% free space on a heavily used XP or OS X system, and I think this was one of the "straws" that pushed my XP system from its usual metastable state to accelerating collapse. In retrospect I'd somehow ended up with a 5GB orphaned pagefile.sys. I couldn't see it, because I somehow had Explorer configured to not show system files . I eliminated the orphaned pagefile.sys by accident , but I think if I'd had Explorer showing me system files I'd have seen it, and dealt with it. New lesson: always display the hidden files so you can track pagefile.sys.
- A combination of Windows Desktop Search , an unstable corporate network with intermittent Exchange connectivity failure, a 3.5 GB Outlook PST file , severe disk fragmentation , bugs with Outlook 2003 , my use of Microsoft's Onfolio , my insanely persistent use of Palm synchronization , Microsoft's Live Meeting Outlook Add-in  finally led to a system meltdown with increasingly odd Outlook behavior and, finally, OST corruption.
- Good news: no covert alerts of drive read/write errors in XP's monitoring tools (XP quietly tracks many disk failures without notifying even admin users) and no chdksk/scandisk/whatever-it's-called-now problems.
So now my OST file was corrupt. Happily, that's usually not a big deal and it wasn't this time either. I turned off WDS (I snoozed indexing but I think I should have disabled the indexing service using XP's service manager - it kept trying to return to life) and found my OS file in "C:\Documents and Settings\[user_id]\Local Settings\Application Data\Microsoft\Outlook". I renamed it and restarted Outlook, which then rebuilt my OST file from the Exchange Server. The new version was about 7MB smaller than the old one (103MB) but I seemed to have everything -- including some old tasks that suddenly reappeared from the twilight zone. I then ran my series of Outlook clean-up switches 
Deletes the logging records saved when a manager or a delegate declines a meeting.
Clears and regenerates free/busy information. This switch can only be used when you are able to connect to your Microsoft Exchange server.
Removes invalid profile keys and recreates default registry keys where applicable.
Clears and regenerates reminders.
Restores missing folders for the default delivery location.
DANGER (don't run this one unless you need it):
Clears and regenerates the Navigation Pane for the current profile. This will vaporize your Outlook Shortcut pane
When all was done I restarted WDS and had it rebuild its index from scratch, then I set my Palm sync to have Outlook overwrite the Palm.
Another fun lunchtime with Microsoft ...
------------- footnotes --------------------
I removed my cache to free up enough space to run defrag, and when I restored a fixed 2GB cache the system asked if I wanted to delete an old pagefile.sys. Then my free space reappeared. A new 160GB high speed drive is on order.
 XP won't defrag when free space is less than 15%. OS X is much less prone to serious fragmentation.
 Still, it's much better than its predecessor.
 XP has the world's best blog writer, Windows Live Writer, but XP's corporate-friendly blog readers are very weak - and getting worse. Onfolio was the best, but Microsoft has left it to fester post acquisition. I fear it's becoming increasingly unsafe. OS X has the opposite problem -- lousy authoring tools, great readers. Of course OS X can also run WLW in a VM ...
 Really, I need all this stuff. But WDS is trying to index 4GB of Outlook and hundreds of thousands of system files.
 If you're not a Palm addict, I beg you, don't start. Life with Palm and Outlook/Exchange is like juggling antimatter, and it gets worse all the time.
 Ok, so this is another straw on that broken back. I am very suspicious of that plug-in and how it impacts Outlook/Exchange behavior with an unreliable network.
 This is typical of whenever I regenerate Outlook's OST file. Something old always reappears, it's never been important. Bugs.
 I do them one at a time exiting Outlook after each one.
 Outlook 2003's Shorcut pane is a "pain in the ***". So dumb, yet so essential in a complex Outlook configuration.
 This is why WDS is not an option.
 This is the default setting, but I always change it. Not this time apparently.Update 9/28/07: Wow. Microsoft is in such bad shape. After all of the above I discovered Windows Desktop Search wasn't working properly -- in ways to diverse and complex to document here.
I found that Microsoft has two somewhat different products they call "Windows Desktop Search". If you Google on WDS you will find the product they aim at the corporate sector. Don't get that version (so called "3.1").
I ended up uninstalling WDS-Corporate-individual user 3.1 I installed the version you get with Windows Live toolbar..
- Install Windows Live Toolbar
- This should install the right version of WDS. If not use "toolbar options" and "install buttons" to find and download WDS...
Update 10/23/07: The saga continued with some improvements as noted above, but then the flakiness returned. In particular Outlook would exit with a hung process, and I'd lose network access. My employer has larded up my system with various inventory services, but, mercifully, does let me disable services. I kept working through the list, disabling various XP services but with little impact. I reviewed my list installed software, and uninstalled various apps I don't use. That' when I noticed a very suspicious Yahoo updater (don't you hate that every damned app has its own update infrastructure?) -- removing that did seem to help my startup time!
The error frequency grew, and it became apparent there was a hardware component to the debacle -- one that wasn't showing up in XP's event logs.
I hate hardware failures -- especially those the OS can't detect.
I replaced the hard drive on the general principle that drive failures are common. If that doesn't work it's time to test memory and even the video memory.