Your personal statement needs to convince the admissions committee that you are motivated and qualified to complete a PhD. Many students do not spend enough time on the second part. Explain why you are interested in research, but also give evidence that you will be successful. It is most helpful if you use the personal statement to give narrative details that cannot be summarized in your CV.
If you are currently enrolled in a domestic graduate program, please also explain in your statement why you are leaving that program. If you have been in contact with a Drexel faculty member before application, please include those details. Your personal statement should be 1-2 pages total.