Most customers prefer to have Windows XP Professional edition installed in their computer while they actually pay more money for this edition even though they are not always if ever use the addition features which are contained in comparison to the Home edition.
To help you decide which is the most suitable edition for your needs, we have summarized the additional features which exist at the Professional edition.
1. Remote Desktop - see full description at "Remote Desktop vs. Remote Assistance" article.
2. Multi-processor support - Home edition support single processor while the Professional edition supports up to two processors
3. Automated System Recovery - see full description at "Howto: Automated System Recovery (ASR)" article.
4. Dynamic Disk Support - A dynamic disk contains dynamic volumes, such as simple volumes, spanned volumes, striped volumes, mirrored volumes, and RAID-5 volumes. With dynamic storage, you can perform disk and volume management without restarting the Windows
5. Fax - built-in fax integrated (in Home edition fax can be explicitly installed via Windows Installation CD-ROM).
6. Internet Information Server - support of web server.
7. File Systems Encryption - ability to encrypt files and folders in order to protect sensitive documents from other users.
8. File level access control - ability to administrate access control even to individual files using control lists.
9. Domain Connection - ability to be part of a domain managed by Active Directory.
10. IntelliMirror - in continuation to the domain belonging, IntelliMirror capabilities include remotely user data management; centrally-managed software installation, repair, updating, and removal; user settings management; and Remote Installation Services (RIS), which allows administrators to remotely install the OS on client systems.
11. Roaming Profiles - ability to logon on any computer on the domain any use the user's customized settings.
12. Multi-language support - support several languages on a single installation.
13. Sysprep - support of pre-defined installation configuration setup made with Microsoft's Sysprep utility which enables installation of the Operating system with no user interaction.
14. Network Monitor - utility which enables visibility of network communication problems.
Taken from http://www.williamaford.com/