I'm dual booting Mandriva/XP pro, using LILO as my boot loader.

Lately, Windows keeps insisting that I need to reboot to install some updates; it goes through the motions of installing updates while it shuts down, but if I boot back into windows, then it downloads and tries to install the updates again.

In the past (before I was running Linux), I had downloaded an update to windows that required a reboot... It acted just like it is now, except that when it rebooted, it installed the updates /after/ rebooting, but /before/ the XP splash screen. My belief is that the MS bootloader was controlling the actual update.
But now, with lilo handling the boot, I think it's not actually installing the update.

Does this sound like familiar to anyone?

If lilo is anything like grub, then it won't be booting Windows directly, but chainloading the Windows bootloader.
So, it shouldn't affect the Windows installation - I think.

Anyway, exactly this garbage with Windows Update has been happening to me as well lately (so it's actually reassuring to hear it happening to others), but I'm not dual-booting on the machine that is afflicted. This machine has no extra partitions, just the standard XP configuration. So I really don't think you should blame lilo. Blame Microsoft - for everything - it's very therapeutic.

No, no... I'm not 'blaming' Lilo.
I'm just trying to remember how the windows pre-boot installer works. I seem to recall that I had to mess with it when I ran partitionmagic (specifically so I could install Linux!!); partitionmagic set itself to run at reboot, before windows took over the HDD... I believe MS has had a few high-level updates that required this sort of installation, and I'm just trying to track down how, and if, windows boots if it's being driven by Lilo rather than the MS loader.

However, I do agree that blaming MS for everything is VERY therapeutic!!