  We present HI and CO(1-0) interferometric observations of 10 comparable-mass
interacting systems obtained at the Very Large Array (VLA) and the Owens Valley
Radio Observatory (OVRO) millimeter array. The primary intent of this study is
to investigate the response of cold gas during the early stages of collision of
massive disk galaxies. The sample sources are selected based on their
luminosity (M_B < -19), projected separation (5-40 kpc), and single dish
CO(1-0) content (S_{CO} > 20 Jy km/s). These selection criteria result in a
sample that primarily consists of systems in the early stages of an interaction
or a merger. Despite this sample selection, 50% of the systems show long HI
tidal tails indicative of a tidal disruption in a prograde orbit. In addition,
all (4/4) of the infrared luminous pairs (LIRGs) in the sample show long HI
tails, suggesting that the presence of a long HI tail can be a possible
signature of enhanced star formation activity in a collision of gas-rich
galaxies. More than half of the groups show a displacement of HI peaks from the
stellar disks. The CO(1-0) distribution is generally clumpy and widely
distributed, unlike in most IR-selected late stage mergers -- in fact, CO peaks
are displaced from the stellar nucleus in 20% (4/18) of the galaxies with
robust CO detection. HI and CO(1-0) Position Velocity Diagrams (PVDs) and
rotation curves are also presented, and their comparison with the numerical
simulation analyzed in Paper I show evidence for radial inflow and wide
occurrences of nuclear molecular rings. These results are further quantified by
examining physical and structural parameters derived in comparison with
isolated systems in the BIMA SONG sample in our forthcoming paper.
