What a fun day I've had!
I set up two new accounts on the desktop - "Keef" (Admin) and "Me" (not admin). The machine set them both up with basic Win XP configs, but neither was accessible from the laptop. "Me" also wasn't allowed to use any of the Office XP, or my Mozilla mail ID, or anything much else, either.
I conclude that whatever removing that User did, it was pretty dire. I'll live with not being able to network the laptop to the desktop (until, maybe, I get a new desktop and can do some hefty CDROM file transfers). Meanwhile, most of the desktop config is back to how it was - the synch to the iPaq was working, then ActiveSynch crashed. That screwed something up in a big way, and I've not got to the bottom of that yet.
Yes, the laptop uses NTFS and the old desktop doesn't. There is no bridge that I can see - there's not enough stuff there to provide one.
I dug around in the Control Panel/Admin Tools and found a lot of red-marked events, mostly missing files or settings. Now reading the instructions and doing a gradual patch job there - and removing some.
Apart from that, it's been a pretty quiet day.