Maskinare

Hi, I have a bunch of Vivotek IP cameras connected to a PC where I record using Vivotek's free software ST7501. As I still have one of my old Sensormatic analog dome's just hanging their, I was thinking that I might be able to insert it together with my IP cameras in ST7501. Does anyone know if it is possible to use a DVR card and some how share this camera into ST7501? Or, I'm I forced to use an expensive analog-to-IP converter?