Dreamworks Animation has become the sixth studio to get on board with Walmart's recently-announced disc-to-digital conversion plan. The announcement comes just in time for the service's launch today, Monday April 16th, and brings titles such as Shrek and How to Train Your Dragon to the lineup already supported by Sony, 20th Century Fox, Universal, Warner Bros, and Paramount. Bringing in a DVD or Blu-ray disc to a physical location will let you add an SD or HD digital copy to your Vudu on-demand library for $2, or you can pay $5 to upgrade a DVD to the HD digital version. You can still hold on to your disc after making the conversion, and Walmart promises Vudu integration with video from other UltraViolet sources, too.