Thank u GOD!
I found out that osCommerce provides a dull user interface. I asked my friend Firdaus from Teras-Solution.com is there any opensource application to cater the e-commerce? Then he introduced me to VirtueMart.
Since I'm going to develop a new website plus the e-commerce facilities, so went to the download area which is here, and selected the Joomla! 1.5 eCommerce Bundle download package.
This installation pack consist of Joomla! 1.5 preInstalled and preConfigured with the VirtueMart e-commerce facilities.
I love Joomla!