JSI Tip 4608. How do I register an Internet browser and/or e-mail client with the Windows XP Start menu?

Microsoft Knowledge Base Article 297878 contains the following summary:

The information in this article applies to independent software vendors (ISVs) who want to register their applications with the Windows XP Start menu. Windows XP has the ability to register a Start menu Internet application either as the computer default or as a per-user default. Windows XP also offers the ability to register a per-user default e-mail client. This article provides detailed information on this new capability.