If you can do it and your client  can't than the first thing to try is running
Repair on Office 2007 from the Control Panel Add/Remove Programs. Installing
individual apps from Office 2003, for example One Note or Visio, will often
confuse the browser on which ActiveX control to use. running  repair will fix
it. Otherwise its something in the settings for your client's browser. These
can be set individually (make sure the site is in Trusted Sites or Local
Intranet zone) or may be enforced by an enterprise through policy settings. Are
your laptop and the client's machine both members of the same domain? Otherwise
you may have different group policy settings.