|If the machine starts to boot to Freebsd then there is a bootable media in the machine. It most likely is able to boot to the hard drive. Bios is seeing the hard drive.|
Fdisk mbr will do nothing for you don't attempt it. A floppy is of no use to you don't waste your time.
Are you sure that when you boot to the XP CD that there is no partition to delete? XP and many other's can't determine what Freebsd might be formatted as. Even a unknown format should be able to be deleted in XP's install enviroment.
There is about 99% chance that XP can access common IDE adapters and drives. There may be a very odd instance of some very large drives for that version of XP. There might be some odd issues with industrial drives that might be solid state. Unlikely in this case.
Open the case and see what type of drive it is. If too large for xp then slipstream to sp3.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10