Here is the take from Microsoft:
You can install one copy of Office Professional Edition 2003, Office Small Business Edition 2003, and Office Standard Edition 2003 on your main computer and another on your laptop computer for your exclusive, but non-concurrent use. To install a version of these Office 2003 Editions on more than these two computers, you must obtain another license for the program. You can install Office Student and Teacher Edition 2003 on up to three computers in your household if a household member is qualified. You can work with Office 2003 Editions at your desk and when mobile. Note Licenses for the 2003 release of Office acquired preinstalled on new computers are single-computer licenses that cannot be transferred or installed on another computer.