 The AdV-tk vector is injected into the tumor or tumor bed at the time of biopsy or standard tumor surgery after which valacyclovir pills are taken for 14 days. Two courses of AdV-tk, each followed by valacyclovir, are given as adjuvant to standard of care therapies surgery andor chemoradiation which have been shown to work cooperatively with AdV-tk to kill tumor cells. Arm A is for resectable tumors in which the first course is given prior to surgery and the second is at the time of surgery. Arm B is for locally advanced disease in which both AdV-tk injections are administered by needle injection into the tumor before and during chemoradiation. The hypothesis is that this combination therapy can be safely delivered and will lead to improvement in the clinical outcome for patients with pancreatic cancer. 