They will have a problem then!
Seriously, for the powerful hardware you have, the performance is very poor. You will notice, that lot of people in this forum can help you, if you are using some sort of Unix. Many of us, at least myself, are clueless in the "closed" Windows environment. You might have a better chance in the Windows-Forum http://moodle.org/mod/forum/view.php?id=6799
> 2. Will Windows Network Load Balance help on this issue?
Load balencing is the classical approach to high performance webservers. See for example http://moodle.org/mod/forum/discuss.php?d=62896
Since your car seems to a have pulled hand-brake, how much a turbo-charger will accellarte it, is a difficult question.
> 3. Many users in the forum suggest that the Moodle is performance much better on Linux based platform, I plan to try out on RHEL4.2., any comments
No operating system is "faster" per se. It depends on how much you understand and able to tune it. The difference between "closed" systems like Microsoft Windows and "open" systems like Linux ist that, the open system is open! You can look in to it, put your hands on it, start tweaking! And the whole fun is free!
Since you suggest RHEL, I guess you have the know-how. In that case, for web-servers at least, Unix is definitely the way to go. For people who want to start from scratch but want to systematically build an understanding of Linux, I've just started a small project. http://moodle.org/mod/forum/discuss.php?d=64984
You, or anybody else who is interested, can write to me personally. Please note that any follow-up discussion on that topic belongs to the thread mentioned above.