We discuss a way to evaluate the full prediction for the interquark potential
which is expected from the effective Nambu-Goto string model. We check the
correctness of the prescription reproducing the results obtained with the zeta
function regularization for the first two perturbative orders. We compare the
predictions with existing Monte Carlo data for the (2+1) dimensional Z(2),
SU(2) and SU(3) gauge theories: in the low temperature regime, we find good
agreement for large enough interquark distances, but an increasing mismatch
between theoretical predictions and numerical results is observed as shorter
and shorter distances are investigated. On the contrary, at high temperatures
(approaching the deconfinement transition from below) a remarkable agreement
between Monte Carlo data and the expectations from the Nambu-Goto effective
string is observed for a wide range of interquark distances.Comment: 25 pages, 4 eps figures; added a reference, included remarks,
corrected a typo; version accepted for publication in JHE