Which one...Home or Pro?
This covers both :
Here's What You Need to Use Windows XP Home Edition
PC with 300 megahertz (MHz) or higher processor clock speed recommended; 233-MHz minimum required;* Intel Pentium/Celeron family, AMD K6/Athlon/Duron family, or compatible processor recommended
128 megabytes (MB) of RAM or higher recommended (64 MB minimum supported; may limit performance and some features)
1.5 gigabyte (GB) of available hard disk space.
Super VGA (800 × 600) or higher resolution video adapter and monitor
CD-ROM or DVD drive
Keyboard and Microsoft Mouse or compatible pointing device
Here's What You Need to Use Windows XP Professional
PC with 300 megahertz or higher processor clock speed recommended; 233 MHz minimum required (single or dual processor system);* Intel Pentium/Celeron family, or AMD K6/Athlon/Duron family, or compatible processor recommended
128 megabytes (MB) of RAM or higher recommended (64 MB minimum supported; may limit performance and some features)
1.5 gigabytes (GB) of available hard disk space
Super VGA (800 × 600) or higher-resolution video adapter and monitor
CD-ROM or DVD drive
Keyboard and Microsoft Mouse or compatible pointing device
Pay close attention to the minimum requirements as well as understanding that additional bits and pieces may be needed to enjoy the full extent of the features XP offers. If your current computer doesn’t meet or substantially exceed these requirements it would almost assuredly be a wiser choice to purchase a new machine with XP preinstalled rather than follow the upgrade path.
Don't know your clock speed. From Intel.com :
Intel's mobile Pentium® II processors at speeds of 400, 366, 333, 300PE, 266PE and 266MHz (low voltage) bring higher performance and more efficient power consumption to mobile computing.
Did you get info from Programs>Accessories>System Tools>System Information? Mine listed my clock speed.
Ron