internet explorer will works only on windows based 
application. i.e., in closed systems.

but nescape navigator(developed in UNIX) will work in open 
system(Unix, Linux) as well as in closed systems(windows).

just i'm expecting. but, not sure.

Internet Explorer is make of Microsfot and
Netscafe Navigator is make of Netscafe

When you are using Internet Explorer (IE) attached
documents created in Microsoft Office (Word, Excel,
PowerPoint) will open up in the content frame. Attached
Office documents in Netscape will ask you if you want to
"download the document to your hard drive" or "open it in
its current location." The former will not open the document
but save it to your computer. The latter will launch the
program in which the document was created.

With IE, pressing the Enter key will activate such buttons
as "Submit" and "Log-in". In Netscape you must actually
click on these buttons.


Note: Netscape does not always work properly. Sometimes
items an instructor adds will not appear where they should,
links may not function properly, etc. This is why it is
strongly encouraged that everyone use Internet Explorer 5.5
or above for all functions of Blackboard. In any case DO NOT
use the AOL browser. Certain functions such as assessments
do not work properly.