[Alneyan]

Isn't all this information supposed to be stored in the MBR? (Or the EMBR, as applicable, and similar records) I know that's where I would expect to find my bootloader link and partition tables stored. Of course, XP isn't very informative either way: this space is labelled as unpartitioned (implying it isn't used at present), but if it really was empty, it isn't terribly useful to show the space up.

On the other hand, if XP is using some other space for a similar purpose, that could explain the difficulties when using this particular OS in a multi-boot. In particular, XP loves to "convert" FAT32 partitions created with fdisk, requiring a reboot afterwards (FAT partitions created via the XP installer are fine), so this could be a consequence of this behaviour.

Do you have any link with more info about this behaviour? I suspect it is linked to XP, since I've never seen it pop up on other OS (my current partition table does not show any unallocated space, if I fill it up to the max).