VISTA awarded a contract to Raytheon Vision Systems in June 2002 to supply 16 SWIR HgCdTe 2Kx2K detectors. Raytheon has delivered VIRGO 2K x 2K readout multiplexers, engineering detectors and the first two science grade detectors. The UKATC has set up a low background test facility to test and characterize the VIRGO detectors and to confirm that the detector performance meets our specifications. The VIRGO 2Kx2K is a new detector being produced for VISTA by Raytheon. In this paper we present the first results and performance of the multiplexer and the science detector. The test facility includes a custom built low background close-cycle cooled cryostat, cryogenic pre-amplifier electronics and uses ESO’s Infrared array controller electronics and detector control and data acquisition software. The detector parameters being measured include trans-impedance conversion gain, quantum efficiency in J, H and K wave bands, read noise, dark generation rate, linearity, well capacity, pixel operability, drift with temperature, persistence and electrical cross-talk.