How do I run an ISO file on Windows XP?

You need a tool that creates a virtual CD/DVD drive and "mounts" the ISO as a virtual CD.

Some famous tools are:

• Daemon Tools (not free anymore :-( )
• Virtual CloneDrive

An ISO is an image of a CD or DVD disc. It contains all the data, and is often used to make multiple copies of an optical disc. You can install the software on it in one of several ways:

• You can burn it to CD/DVD using tools like ImgBurn or Nero, and then use the CD like normal;
• You can mount it in a "fake" CD drive using Virtual CloneDrive or Daemon Tools; or
• You can use a program such as MagicISO to extract files from it.

WinCDEmu is an open-source software that allows mounting CD/DVD images by clicking at the image files in Windows Explorer. It supports both Windows XP and Vista

it doesn't get much easier :)

WinCDEmu is open-source and freeware.

You need to install something like Virtual CD or the Microsoft Virtual CD Control Panel (direct link to exe)

This will then allow you to read or "mount" the ISO file as though it were a real CD or DVD.