The "online" installation frequently fails. Follow the instructions in the link below:

Click on the link to Sun's Java below, then click on the ''Java Runtime Environment (JRE) 6u3'' download button. Follow the prompts, accept the license agreement, then download the full ''Windows Offline Installation'' file to your desktop,(about 15 MB), scan it with your antivirus (just to be sure it's clean). Once that's done, if you've already got a Sun Java version on the computer, open the Control Panel, double click on the ''Add/Remove Programs'' section, then uninstall all previous versions of the J2SE Java listed there. Once that's done, then install Java JRE 6u3 from the downloaded installer.

http://java.sun.com/javase/downloads/index.jsp

Once Java is installed, since you're using IE7, then access the Internet Explorer "Internet Options" settings, "Security" tab, "Internet" icon, "Custom Settings" and change the security level to "Medium", instead of "Medium-High".

Hope this helps.

Grif