This theme changes around 10 core osCommerce files so is easy to install even onthe most modified of sites. Have a look at the demo.
It is a 1 column design, so there is lots of available space on every page for promoting your products. It has a horizontal menu (with dropdowns), along with a much nicer footer area. Of course, the “new products” module is also updated.
The cost of this template? Just £16 (approx $25), and you could even get it for free by purchasing the “design oscommerce” ebook. If you would like to see my other templates I’ve recently built head over to choices page.