computer technology

You can create a boot disk from either My Computer, Disk Manager, or Windows Explorer.

To create a true XP startup disk (actually a several disk set) you need to download the correct file to create the startup disk set for the version of XP that you intend to install.

At last count, there were 4 different versions of the startup disk set:
Home
Pro
Home SP1
Pro SP1

Microsoft assumed that everyone would have PCs that support booting from the CD when installing XP.

Additional resources include:

www.bootdisk.com
www.madboot.com

Chas