Thank you giantjoebot and all other respected members,
I have finally reinstalled the Windows XP and reactivated it. Yes I am feeling the difference between performance, as giantjoebot said that if I switch back to my older cpu after the fresh installation of windows, I would see the same performance at some extent.
He is true, but I am feeling the real performance boost after reinstalling the windows. I have been using computer since 1997. I am also involved in Computer Related Business, but sometimes a point comes that you cannot decide for yourself what is better and what is not?
I am still not convinced by Microsoft. Because Microsoft should announce a patch for the Dual-Core Processor.
Another important thing: Microsoft has mentioned a Performance Hole in this article and say us to be patience and wait for Service Pack 3 of Windows XP to get the maximum performance boost when using Dual Core.
The link is: Click Here
I have also experimented the same reinstallation method on Windows Vista RC1, and I have really felt the performance boost on that window, it seems that Windows Vista RC1 is utilizing the true benefits of the Dual Core Architecture.
In my experiment, first I had clean install Windows Vista RC1 on the Older CPU i.e. P4 3.0 GHz 2MB Cache with HT and then I have again clean install Windows Vista using Pentium D 3.40 GHz. (945) the difference was very clear.
I have also checked by creating a HD Clip using Windows Movie Maker on Vista and felt the difference.
No doubt the Dual Core CPUs are very must responsive and fast than HT.
I hope that my explanation would be very beneficial for others.
Whenever, you change the following hardware do a reinstall:
and when you change the RAM upgrade/degrade, don't forget to adjust the virtual memory settings.
Thanks to everyone.