I'm not sure about Windows 7, but in Windows XP you have to install Asian Language support for Windows. Control Panel -> Regional and Language Settings You need to hit the checkbox for East Asian Language support. After that, it gets a bit tricky in terms of understanding how to pull up the language bar. Once you've gotten language bar up In general, I think the main toggle is CTRL-Space (and sometimes you need to hit the Left-Shift button to adjust between typing Chinese and English. Once you've got that set up, you can use the other input methods, including Sogou and Google. I prefer the Google one, but I've heard they are very similar. http://www.google.com/ime/pinyin/ Aside from that, we're generally assumes you're using pinyin 拼音 to write characters. If you're using linux, I think you can install SCIM (smart common input method) system. It should be easy to find, depending on your linux distribution. Here's another answer with this http://www.italki.com/answers/question/16704.htm

the above mentiond chinese input method is named Sogo input method which can input chinese characters and english very conveniently, and it is one of the mostly used input methods currently.

if u cannot read the chinese characters on the download icon, right clike on this linkage and youll get the access to download http://ime.sogou.com/dl/sogou_pinyin_431d.exe