To make it easy to connect to your computer anywhere, Microsoft has invented a new system called the "Windows Internet Computer Name". This is basically a unique domain name for your PC.
There is one small catch though: you have to be using the next-generation networking protocol IPv6 which, although thoroughly integrated into Windows Vista, isn't supported by most home routers yet.
The Windows Internet Computer Name is an advancement on the Peer Name Resolution Protocol (PNRP), which is a name registration and resolution protocol initially developed for Windows XP.
Unlike traditional DNS, where domain name servers are used essentially to store a list of domain names and their corresponding numeric IP addresses, PNRP does all the domain name resolution peer-to-peer. Put another way, users of Windows Vista provide PNRP domain name resolution services for other Windows Vista users.