I have been out of education since 2005 and I still ask my lecturers for references (although since this is my 3rd year of applying for funded PhDs I think they will be getting sick of it now!) I think that your dissertation supervisors from masters or undergrad will still remember you and should be happy to supply a reference - 2003 wasn't that long ago and many academics get reference requests from people who graduated up to 20 years ago!
Perhaps you could use one academic referee and one from work? Although your job may not be relvent to the PhD it is often an advantage to go into a PhD with some years experience of work and many of the skills you have picked up during work (being able to work independently, leadership, skills you have learned) are relevent to a PhD.