See www.annoyances.org for lots of useful information.
To answer your specific question here is a copy of the FAQ re XP home vs Pro from there
What's the difference between Windows XP Home and Professional editions?
Intended For
Windows XP only
The Home and Professional editions of Windows XP are nearly identical; the only differences are additional features found in the Professional edition that most likely won't appeal to home users. The primary differences, aside from the price and the color of the packaging, are as follows:
Windows XP Home Edition
* Contains basic support for security among multiple users.
* Built-in support for peer-to-peer networking, but only for up to five computers.
* The backup utlity is not installed by default, but is included on the CD.
Windows XP Professional Edition
* Includes extended support for security between multiple users on the same machine.
* Better support for peer-to-peer networking, plus support for joining a "Windows NT domain."
* The backup utlity is installed by default.
* The Professional edition includes the following components not found in the Home edition:
o Administrative Tools (in the Start Menu and Control Panel)
o Automated System Recovery (ASR)
o Boot Configuration Manager
o DriverQuery
o Group Policy Refresh Utility
o Multi-lingual User Interface (MUI) add-on
o NTFS Encryption Utilitiy
o Offline Files and Folders
o OpenFiles
o Performance Log Manager
o Remote Desktop
o Scheduled Tasks Console
o Security Template Utility
o Taskkill
o Tasklist
o Telnet Administrator
* Provides support for multi-processor systems (2 or 4 CPUs), Dynamic Disks, Fax.
These components and concepts are fully documented in Windows XP in a Nutshell, the book.
IMO, most critical advantages of the Pro version are, in order:
1) support for NT Domains - especially if you are using a notebook system for work - most workplaces use some flavour of DNS and the home version will NOT connect to these networks. Better support for peer to peer is also good.
2) the additional admin features are a good thing to have for both maintenace and trouble-shooting purposes.
3) despite the fact that MS has an extremely poor record re security, any improvements / additional capabilities in this area that the OS provides are no longer a "luxury", given to-day's security environment. They are as obligatory as oxygen is to life.
My recommendation is to get the Pro version.
If you go with the Home version, you can buy the upgrade to Pro on a seperate CD from MS, but you will not save any money and the installation prcess will be that much more cumbersome.
Hope this helps.