Hi Ackerberg, I think the limitation is usually BIOS. Most large drives will need the latest BIOS update to enable more than 32Gb. Some can do it automatically but I would check whether the HD manufacturer advises updates. Neil.
2TB is the limit imposed by the NTFS partition table, so a single drive can't be larger then 2TB (unless you start tweaking sector size, taking that from 512 bytes to 4KB will let XP handle up to 16TB).