Hallo Tatenda, happy new year to you :)
I can help you with your question, and the short answer is Magento.
I have done open heart surgery on osCommerce, and really enjoyed using osCommerce.
Below is my hobby site www.3am.co.za, has done in excess of 2500 orders, with over 4500 registered users, it's build on osCommerce, if you want to see it in action, download some Free Stuff, here, http://www.3am.co.za/catalog/free-stuff/index.php/cPath/380
But the fact of the matter for me is that osCommerce has had it's time, Magento is the future certainly, it's documentation is outstanding, with regular release updates and significant features, things like data export functions, a solid administration interface, and countless more makes me glad that Magento came along.
You can have a look at http://www.ktmcapetown.co.za - which is build on Magento and Wordpress integrated to handle the community side of things, the possibilities are endless and although Magento has a steep learning curve, even the clients Rock at it in no time at all,
I could talk your ears of your head, and go on all day, but if you need more info, just let me know,
All the best