I assume you mean when INSTALLING XP?
If so, check the product requirements-this usually hapens
because you don't have a FAT formatted hard drive
partition of sufficient size for the installation (I
believe it checks for 1 gig of free space, not sure on the
number).
I don't believe XP will use a FAT32 drive for
installation, although it can use FAT32 after it's
installed.
When running XP setup, don't let it use the existing
partition/formatting. Have setup repartion/reformat-this
will guarantee a format XP likes.
Be sure you don't want any of the existing data that's on
the drive, as partition or formatting will permanently
erase any data on there!
When I do installs I use Partition Magic so I can
create/change partitions without losing my data (provided
I don't delete the partition with the data in it).Plus it
allows me greater control of my drive space (it can
hide/unhide primary partitions).
Good luck, and remember to check the requirements.