Be aware when you install whatsapp on your computer! DO NOT USE ANY APK IN THE WEB, it's infected by viruses and contains a lot of ads.

With the new updates of whatsap , you need also special recommendations to install that on your PC

Source: http://supplysystems.com/2014/02/01/download-whatsapp-for-pc-windows-x7-xp/

Collen, I'm not agree with you. you can install Whatsapp as many android app on your PC with the help of android emulator. Here is an example of tutorial: http://www.emoretech.com/whatsapp-for-pc-download-free-whatsapp-windows78vista/ . Install first an android emulator and get the apk of whatsapp and it's done. Of course it less confortable on pc like on smartphone, but you can do that.

Hope it helps