Old SLR lenses

I've got an old Pentax MV with a couple manual focus lenses. I've got a digital point and shoot but as my daughter grows older I'm not happy with my inability to control the depth of field. So I'm considering upgrading to a DSLR and just using my old manual focus lenses. Am I kidding myself into thinking this is possible? Or should I just go ahead and factor in a new lens or 2 into the price of a new setup.