Namebench

Works with: Windows 7, Vista

Read more about Namebench here:
http://code.google.com/p/namebench/

One way to speed up your Internet browsing experience is using a faster DNS server. If you’re looking for a tool to help find a faster DNS server for your system, Namebench is your answer. This small, free utility performs benchmark tests on multiple DNS servers, reports back on which are the fastest, which the most secure, and so on, and recommends which DNS servers you should use. Once you get that recommendation, it's up to you to configure your PC to use the fastest DNS servers.