If you are using Windows 7 then the best software to use is proxy switcher. However, keep in mind that as Windows 7 becomes more popular and wide spread there will be many more software vendors that go about making proxy server related software. The best IP rotating programs should allow you to use multiple IPs, offer several different methods of rotation and include some kind of timeout feature so that the program skips to your next proxy if the current one times out. Be sure that it works with HTTP proxies or elite proxies as this is the most popular kind of proxy server.
If you just have one proxy that you use, then there is probably very little need for any kind of software to rotate your IPs. However, if you have multiple IPs that you constantly need to rotate through it can be very difficult and time consuming if you need to do it by hand. Most people use proxies via some kind of internet web browser and changing your IP is very slow. The solution? IP rotating software. With the click of a button you can switch IPs within seconds, making a time consuming process now simple and easy.
Looking for an elite proxy rotator for Windows 7? This is much easier than it sounds because the majority of software available is still built for Windows XP or Windows Vista at best. The most popular rotating proxy software is called proxyfirewall. Why would you even need software to rotate IPs?