Scott,
I don't know of any way that partitioning or formatting a drive can affect the BIOS but, if you somehow partitioned the drive without making your boot partition the 'active' partition, then the BIOS wouldn't find your Windows XP files to boot from. Of course, if you created the partitions during the Windows XP install as your original post seemed to suggest, then it looks like it just messed it up a bit itself.
Anyway, thanks for the feedback