http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B314343
Once again, the above article striaght from Bill Gates and revised on December 1, 2007, which seems rather up to date to me:
Article ID : 314343
Last Review : December 1, 2007
Revision : 3.2
Basic Storage Versus Dynamic Storage in Windows XP
You cannot create mirrored volumes or RAID-5 volumes on Windows XP Home Edition, Windows XP Professional, or Windows XP 64-Bit Edition-based computers. However, you can use a Windows XP Professional-based computer to create a mirrored or RAID-5 volume on remote computers that are running Windows 2000 Server, Windows 2000 Advanced Server, or Windows 2000 Datacenter Server. You must have administrative privileges on the remote computer to do this.
"Without a hardware RAID controller"
