I agree with the others: Wilcom's Truesizer works well, download it and resize from your original pes design NOT from the resized and reformatted vp3. With every step information gets lost and the end result might be unsatisfactory!
I have the free version of Wilcom and it will change the format for you. Just save the design in PES in stead of vp3. Hope that helps. Embroidery Designs also have a site to change formats. I used that before I found Wilcom.
I think you need a program like wilcom true sizer it is a free download,