Not very keen to post about this but a good tool to work with existing Powerpoint resource.PPT Minimizer is a useful tool to reduce the size of Powerpoint Presentation and could be downloaded from (www.pptminimizer.com).
Though allows only 12 presentations to optimize but worth a try and use. The best part is it saves the optimized presentation in the .ppt format only. Personally, have been able to reduce the size upto 85%.
