Would you consider yourself a "power user"?
Windows XP Professional contains a number of incremental features too numerous to list here. Suffice it to say, users who demand the most from their computers will want to "go Pro." Some additional features found only in Windows XP Professional are:
Advanced networking for multiple PC environments
Internet Information Services (IIS), a Windows XP Professional feature that lets you host and manage personal Web sites
Support for multiple-processor systems
Support for multiple languages
The Encrypting File System (EFS), found in Windows XP Professional but not Windows XP Home Edition, allows you to encrypt your files and folders for added security of sensitive data against theft or hackers. Restricted File Access, also found only in Professional, allows you to restrict access to selected files, applications, and other resources